I had something similar to this, it stopped the next time i opened my world editor up:
I opened my map and then a load of custom units from "Autumn Crossing TD" were in the object editor.
Luckilty, it is sorted now. If you're having the smae problem, restart your computer, if that fails, ask here (done) and if all else fails, ask on battle.net forums (blizzard do not support editor so don't contact them).
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.