diff --git a/__tests__/datalib/judgeToTeam.ts b/__tests__/datalib/judgeToTeam.ts
new file mode 100644
index 00000000..fb685794
--- /dev/null
+++ b/__tests__/datalib/judgeToTeam.ts
@@ -0,0 +1,132 @@
+import { db } from '../../jest.setup';
+import { GetJudgeToTeamPairings } from '@datalib/judgeToTeam/getJudgeToTeamPairings';
+import { ObjectId } from 'mongodb';
+import JudgeToTeam from '@typeDefs/judgeToTeam';
+
+beforeEach(async () => {
+  await db.collection('submissions').deleteMany({});
+});
+
+// Helper to create valid submission documents
+function createSubmission(judgeId: ObjectId, teamId: ObjectId) {
+  return {
+    judge_id: judgeId,
+    team_id: teamId,
+    social_good: null,
+    creativity: null,
+    presentation: null,
+    scores: [],
+    is_scored: false,
+    queuePosition: null,
+  };
+}
+
+describe('GetJudgeToTeamPairings', () => {
+  it('should return an empty array when no submissions exist', async () => {
+    const result = await GetJudgeToTeamPairings();
+    expect(result.ok).toBe(true);
+    expect(result.body).toEqual([]);
+    expect(result.error).toBe(null);
+  });
+
+  it('should return pairings with string IDs converted from ObjectIds', async () => {
+    const judgeId = new ObjectId();
+    const teamId = new ObjectId();
+
+    await db
+      .collection('submissions')
+      .insertOne(createSubmission(judgeId, teamId));
+
+    const result = await GetJudgeToTeamPairings();
+    expect(result.ok).toBe(true);
+    expect(result.body).toHaveLength(1);
+    expect(result.error).toBe(null);
+
+    const pairing = result.body?.[0];
+    expect(pairing).toEqual({
+      judge_id: judgeId.toString(),
+      team_id: teamId.toString(),
+    });
+  });
+
+  it('should return multiple pairings correctly', async () => {
+    const judgeId1 = new ObjectId();
+    const judgeId2 = new ObjectId();
+    const teamId1 = new ObjectId();
+    const teamId2 = new ObjectId();
+    const teamId3 = new ObjectId();
+
+    await db
+      .collection('submissions')
+      .insertMany([
+        createSubmission(judgeId1, teamId1),
+        createSubmission(judgeId1, teamId2),
+        createSubmission(judgeId2, teamId3),
+      ]);
+
+    const result = await GetJudgeToTeamPairings();
+    expect(result.ok).toBe(true);
+    expect(result.body).toHaveLength(3);
+    expect(result.error).toBe(null);
+
+    const pairings = result.body as JudgeToTeam[];
+    expect(pairings[0]).toEqual({
+      judge_id: judgeId1.toString(),
+      team_id: teamId1.toString(),
+    });
+    expect(pairings[1]).toEqual({
+      judge_id: judgeId1.toString(),
+      team_id: teamId2.toString(),
+    });
+    expect(pairings[2]).toEqual({
+      judge_id: judgeId2.toString(),
+      team_id: teamId3.toString(),
+    });
+  });
+
+  it('should handle duplicate judge-team pairings', async () => {
+    const judgeId = new ObjectId();
+    const teamId = new ObjectId();
+
+    await db
+      .collection('submissions')
+      .insertMany([
+        createSubmission(judgeId, teamId),
+        createSubmission(judgeId, teamId),
+      ]);
+
+    const result = await GetJudgeToTeamPairings();
+    expect(result.ok).toBe(true);
+    expect(result.body).toHaveLength(2);
+
+    const pairings = result.body as JudgeToTeam[];
+    expect(pairings[0]).toEqual(pairings[1]);
+  });
+
+  it('should convert ObjectIds to strings for duplicate prevention comparison', async () => {
+    const judgeId = new ObjectId();
+    const teamId = new ObjectId();
+    const judgeIdString = judgeId.toString();
+    const teamIdString = teamId.toString();
+
+    await db
+      .collection('submissions')
+      .insertOne(createSubmission(judgeId, teamId));
+
+    const result = await GetJudgeToTeamPairings();
+    const pairings = result.body as JudgeToTeam[];
+
+    // This test verifies that String() conversion is necessary for comparison
+    // in algorithms like judgesToTeamsAlgorithm.ts
+    expect(String(pairings[0].judge_id)).toBe(judgeIdString);
+    expect(String(pairings[0].team_id)).toBe(teamIdString);
+
+    // Simulate the duplicate check from judgesToTeamsAlgorithm.ts (lines 183-189)
+    const duplicateExists = pairings.some(
+      (entry) =>
+        String(entry.judge_id) === judgeIdString &&
+        String(entry.team_id) === teamIdString
+    );
+    expect(duplicateExists).toBe(true);
+  });
+});
diff --git a/app/(api)/_actions/logic/applyDiagnosticAlpha.ts b/app/(api)/_actions/logic/applyDiagnosticAlpha.ts
index cb26d70b..b77aa4f8 100644
--- a/app/(api)/_actions/logic/applyDiagnosticAlpha.ts
+++ b/app/(api)/_actions/logic/applyDiagnosticAlpha.ts
@@ -14,25 +14,35 @@ import checkMatches from '@actions/logic/checkMatches';
 export default async function applyDiagnosticAlpha(options: {
   alpha: number;
   judgeToTeam: JudgeToTeam[];
-}): Promise<{ ok: boolean; body: JudgeToTeam[] | null; error: string | null }> {
+}): Promise<{
+  ok: boolean;
+  body: JudgeToTeam[] | null;
+  error: string | null;
+  message?: string;
+}> {
   const existing = await GetManySubmissions();
-  if (existing.ok && existing.body && existing.body.length > 0) {
+  const teamsRes = await GetManyTeams();
+  if (!teamsRes.ok) {
     return {
       ok: false,
       body: null,
-      error:
-        'Submissions collection is not empty. Please clear before applying diagnostics.',
+      error: `GetManyTeams error: ${teamsRes.error}`,
     };
   }
-  const teamsRes = await GetManyTeams();
-  if (!teamsRes.ok) {
+  const teams = teamsRes.body;
+  const existingCount = existing.ok && existing.body ? existing.body.length : 0;
+  const maxTotalAssignmentsPerTeam = 4;
+  const maxSubmissions = teams.length * maxTotalAssignmentsPerTeam;
+  const isSecondRound = existingCount > 0;
+
+  if (existingCount >= maxSubmissions) {
     return {
       ok: false,
       body: null,
-      error: `GetManyTeams error: ${teamsRes.error}`,
+      error:
+        'Maximum judge assignments reached (4 judges per team). Clear submissions to rerun.',
     };
   }
-  const teams = teamsRes.body;
   const parsedSubmissions = await parseAndReplace(options.judgeToTeam);
   if (!checkMatches(parsedSubmissions, teams.length)) {
     return {
@@ -62,5 +72,12 @@ export default async function applyDiagnosticAlpha(options: {
   //     return { ok: false, body: null, error: res.error };
   //   }
 
-  return { ok: true, body: options.judgeToTeam, error: null };
+  return {
+    ok: true,
+    body: options.judgeToTeam,
+    error: null,
+    message: isSecondRound
+      ? 'Second round detected: new pairings were added on top of existing submissions.'
+      : undefined,
+  };
 }
diff --git a/app/(api)/_actions/logic/checkMatches.ts b/app/(api)/_actions/logic/checkMatches.ts
index 54fe18f8..6068cc87 100644
--- a/app/(api)/_actions/logic/checkMatches.ts
+++ b/app/(api)/_actions/logic/checkMatches.ts
@@ -4,7 +4,7 @@ export default function checkMatches(
   matches: Submission[],
   teamsLength: number
 ) {
-  if (matches.length < 3 * teamsLength) return false;
+  if (matches.length < 2 * teamsLength) return false;
 
   let valid = true;
   const mp: Map<string, number> = new Map();
@@ -18,7 +18,7 @@ export default function checkMatches(
   }
 
   mp.forEach((count) => {
-    if (count !== 3) valid = false;
+    if (count !== 2) valid = false;
   });
 
   return valid;
diff --git a/app/(api)/_actions/logic/matchTeams.ts b/app/(api)/_actions/logic/matchTeams.ts
index 157245ce..b58fa5a5 100644
--- a/app/(api)/_actions/logic/matchTeams.ts
+++ b/app/(api)/_actions/logic/matchTeams.ts
@@ -5,13 +5,13 @@ import matchAllTeams from '@utils/matching/judgesToTeamsAlgorithm';
 import parseAndReplace from '@utils/request/parseAndReplace';
 import { GetManyTeams } from '@datalib/teams/getTeam';
 import { CreateManySubmissions } from '@datalib/submissions/createSubmission';
-import { GetManySubmissions } from '@datalib/submissions/getSubmissions';
+//import { GetManySubmissions } from '@datalib/submissions/getSubmissions';
 import checkMatches from '@actions/logic/checkMatches';
 
 export default async function matchTeams(
   options: { alpha: number } = { alpha: 4 }
 ) {
-  const submissionsResponse = await GetManySubmissions();
+  /*const submissionsResponse = await GetManySubmissions();
   if (
     submissionsResponse.ok &&
     submissionsResponse.body &&
@@ -23,7 +23,7 @@ export default async function matchTeams(
       error:
         'Submissions collection is not empty. Please clear submissions before matching teams.',
     };
-  }
+  }*/
 
   // Generate submissions based on judge-team assignments.
   const teamsRes = await GetManyTeams();
@@ -46,10 +46,13 @@ export default async function matchTeams(
     }
     const res = await CreateManySubmissions(parsedJudgeToTeam);
     if (!res.ok) {
+      console.log(`${res.error}`);
       return {
         ok: false,
         body: null,
-        error: 'Invalid submissions.',
+        error: `Failed to create submissions in database: ${
+          res.error ?? 'Unknown error'
+        }`,
       };
     }
     // for (const submission of parsedJudgeToTeam) {
@@ -65,7 +68,7 @@ export default async function matchTeams(
     return {
       ok: false,
       body: null,
-      error: 'Invalid submissions.',
+      error: 'Invalid submissions: assignment validation failed.',
     };
   }
   return {
diff --git a/app/(api)/_datalib/judgeToTeam/getJudgeToTeamPairings.ts b/app/(api)/_datalib/judgeToTeam/getJudgeToTeamPairings.ts
new file mode 100644
index 00000000..86bb5fc5
--- /dev/null
+++ b/app/(api)/_datalib/judgeToTeam/getJudgeToTeamPairings.ts
@@ -0,0 +1,28 @@
+import JudgeToTeam from '@typeDefs/judgeToTeam';
+import { getDatabase } from '@utils/mongodb/mongoClient.mjs';
+import { HttpError } from '@utils/response/Errors';
+import Submission from '@typeDefs/submission';
+import { ObjectId, Db } from 'mongodb';
+
+type MongoSubmission = Omit<Submission, 'judge_id' | 'team_id'> & {
+  judge_id: ObjectId;
+  team_id: ObjectId;
+};
+
+export const GetJudgeToTeamPairings = async () => {
+  try {
+    const db = (await getDatabase()) as Db;
+    const submissions = await db
+      .collection<MongoSubmission>('submissions')
+      .find()
+      .toArray();
+    const pairings = submissions.map((submission) => ({
+      judge_id: String(submission.judge_id),
+      team_id: String(submission.team_id),
+    }));
+    return { ok: true, body: pairings as JudgeToTeam[], error: null };
+  } catch (e) {
+    const error = e as HttpError;
+    return { ok: false, body: null, error: error.message };
+  }
+};
diff --git a/app/(api)/_utils/matching/judgesToTeamsAlgorithm.ts b/app/(api)/_utils/matching/judgesToTeamsAlgorithm.ts
index ddad3c8f..9d029252 100644
--- a/app/(api)/_utils/matching/judgesToTeamsAlgorithm.ts
+++ b/app/(api)/_utils/matching/judgesToTeamsAlgorithm.ts
@@ -6,6 +6,7 @@ import { optedHDTracks, nonHDTracks } from '@data/tracks';
 
 import { GetManyUsers } from '@datalib/users/getUser';
 import { GetManyTeams } from '@datalib/teams/getTeam';
+import { GetJudgeToTeamPairings } from '@datalib/judgeToTeam/getJudgeToTeamPairings';
 
 interface Judge {
   user: User;
@@ -66,7 +67,7 @@ export default async function matchAllTeams(options?: { alpha?: number }) {
   const teamMatchQualities: { [teamId: string]: number[] } = {};
   const teamJudgeDomainTypes: { [teamId: string]: string[] } = {};
 
-  const rounds = 3;
+  const rounds = 2;
   const ALPHA = options?.alpha ?? 4;
   // Fetch all checked in judges.
   const judgesResponse = await GetManyUsers({
@@ -157,6 +158,19 @@ export default async function matchAllTeams(options?: { alpha?: number }) {
       .filter((team) => team.tracks.length < rounds)
       .map((team) => [team._id ?? '', rounds - team.tracks.length])
   );
+
+  // Get previous pairings and push it to the judgeToTeam array (so that !duplicateExists is true)
+  const previousPairings = await GetJudgeToTeamPairings();
+  if (!previousPairings.ok || !previousPairings.body) {
+    throw new Error(
+      `Failed to load existing judge-to-team pairings: ${
+        previousPairings.error ?? 'Unknown error'
+      }`
+    );
+  }
+  const previousPairingsBody = previousPairings.body;
+  judgeToTeam.push(...previousPairingsBody);
+
   // Main loop: process each team for each round.
   for (let domainIndex = 0; domainIndex < rounds; domainIndex++) {
     for (const team of modifiedTeams) {
@@ -168,10 +182,14 @@ export default async function matchAllTeams(options?: { alpha?: number }) {
 
       let selectedJudge: Judge | undefined = undefined;
       for (const judge of judgesQueue) {
+        // String() conversion is necessary because:
+        // - previousPairings from GetJudgeToTeamPairings converts ObjectIds to strings
+        // - judge.user._id and team._id are ObjectIds that need .toString()
+        // - Comparing without String() would cause false negatives in duplicate detection
         const duplicateExists = judgeToTeam.some(
           (entry) =>
-            entry.judge_id === judge.user._id?.toString() &&
-            entry.team_id === team._id?.toString()
+            String(entry.judge_id) === judge.user._id?.toString() &&
+            String(entry.team_id) === team._id?.toString()
         );
         if (!duplicateExists) {
           selectedJudge = judge;
@@ -212,6 +230,25 @@ export default async function matchAllTeams(options?: { alpha?: number }) {
     shuffleArray(modifiedTeams);
   }
 
+  // Remove the previous pairings without relying on array insertion order.
+  if (previousPairingsBody.length > 0) {
+    const previousPairingKeySet = new Set(
+      previousPairingsBody.map((pairing) => {
+        const judgeId = String(pairing.judge_id);
+        const teamId = String(pairing.team_id);
+        return `${judgeId}::${teamId}`;
+      })
+    );
+    const filteredJudgeToTeam = judgeToTeam.filter((entry) => {
+      const judgeId = String(entry.judge_id);
+      const teamId = String(entry.team_id);
+      const key = `${judgeId}::${teamId}`;
+      return !previousPairingKeySet.has(key);
+    });
+    judgeToTeam.length = 0;
+    judgeToTeam.push(...filteredJudgeToTeam);
+  }
+
   console.log('No. of judgeToTeam:', judgeToTeam.length);
 
   const judgeAssignments = judgesQueue.map((judge) => judge.teamsAssigned);
diff --git a/app/(pages)/admin/_components/JudgeTeamGrouping/JudgeTeamGrouping.tsx b/app/(pages)/admin/_components/JudgeTeamGrouping/JudgeTeamGrouping.tsx
index aabb46a0..18c021ab 100644
--- a/app/(pages)/admin/_components/JudgeTeamGrouping/JudgeTeamGrouping.tsx
+++ b/app/(pages)/admin/_components/JudgeTeamGrouping/JudgeTeamGrouping.tsx
@@ -130,6 +130,9 @@ export default function JudgeTeamGrouping() {
       setShowSubmissions(true);
       setApplyAlphaSuccess(true);
       setError('');
+      if (res.message) {
+        alert(res.message);
+      }
     } else {
       setError(res.error!);
       setShowMatching(false);
@@ -326,14 +329,14 @@ export default function JudgeTeamGrouping() {
 
   return (
     <div className={styles.body}>
-      <div className="flex items-center gap-4">
-        <h4 style={{ cursor: 'pointer' }}>Error</h4>
-        {error && (
+      {error && (
+        <div className="flex items-center gap-4">
+          <h4 style={{ cursor: 'pointer' }}>Error</h4>
           <div>
             <pre style={{ color: 'red' }}>{error}</pre>
           </div>
-        )}
-      </div>
+        </div>
+      )}
 
       {/* Diagnostics inputs */}
       <div className="mt-6">