Hi Macks, I mentioned an issue in my pull request. This error has been present for a while but is really pronounced in the eval() done to verify that the file created is able to be loaded. Basically the protobuf classes are not tolerant of being re-required.
http://gist.github.com/407742
What I think it should do is probably throw away the old definition if it is re-required but I wanted to get your opinion and input on the cleanest way to do that rather than go in with a machete myself.