Some modules are defined twice?

[ijiraq]

I note that some classes and procedures are defined at least twice (merr
in magerr.py and distributions.py; HDistribution in distributions.py and
models.py)

Likely this is from the reorg and should be fixed

@jmpetit

[jmpetit]

Since the reorg of python is your work, I'll leave it to you to fix this.