But see, I get no errors with BioFreak on vanilla MAME. CMP validates it perfectly, no errors at all. It's just with M32+ that that message appears.

And I'm not "mixing" anything, per se. I'd rather not have one huge folder full of ROMS that CMP would see as "unneeded", if I were to check that option (and I usually do).

I like to keep things seperate like that for my own organization. As I said, I'm probably using CMP in an abnormal way.