Depends how the software handles it. I use Silo to create morphs, and for that I need welded OBJs. Silo removes unused vertices without notice, so usually the vertex count is different, I wasn't able to fix that with UV-Mapper.

The best option for me so far is the PoserMorphLoader from ColorCurvature, but this tool isn't available at the moment. I have no idea if he plans to rerelease it.

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.