The language is user-specified in the code snippet submission form. That means that users can specify abbreviations of the language, misspelling, etc., and they will all appear in separate categories. I suppose someone (me?) should rename them so the naming is consistent.
I remember having that problem, I accidently set the snippet programming language to CPP instead of CPLUSPLUS which showed up in its own catagory. Seems to have been fixed now, but it would have been nice to be able to edit that at the time :-/