Turns out before mGalaxy 6 the game was referred to as "Ms. Pac-Man (with speedup hack)" but NOW mGalaxy 6 saves it in Favorites.ini as "Ms. Pac-Man (speedup hack)"
I can't see mGalaxy changing the description of a game!!
To me, you're using a different mame release and there has been changes in some file descriptions between releases.
Check the mame version you're using with your mGalaxy v5 setup and the mame version you're using with your mGalaxy v6 setup...I'm pretty sure this is not the same!
Not sure why it couldn't use the universal ROM name so this didn't happen.
From my understanding the mame files name change very often (the name of the zip file)...where the description stay the same.
So it sounds to me as a good idea to track a game on its description rather than its .zip set name...but I could be wrong so if there's any MAME specialist reading this post, please confirm what I'm saying ;-)