Hi, gdm appears to duplicate the path when a user logs in, e.g. PATH=$PATH:$PATH I've tested this with several windowmanagers executed from gdm, and all seem to display the problem. Starting X and said windowmanagers from the command line with xinit doesn't display the problem, thus I think it exists somehwere in gdm. grep through GDM's config tree, I couldn't find anything that would seem to duplicate the path, so I'm guessing its something in the code.
Can't reproduce here. The PATH does seem to get a couple of duplicate entries, but the whole path is definitely not doubled, and the duplication is merely a cosmetic defect. This may just be the system-wide or user profile doing its usual.