There ya go! Glad you figured it out. Yeah, I don’t know why RetroPie has both Mega Drive and Genesis as separate systems. Yet, doesn’t do the same for Famicom/NES, Super Famicom/SNES, PC Engine/Turbo Grafix and so on. It’s a little confusing. You should have folders for each, and put the roms in whichever system you want to use. Possibly add a readme in the ROMs folder explaining which systems have multiple names depending on region.