I guess now it's correct. Games with a BIOS (STV, Super Kaneko, etc.) are CLONES of that BIOS and filtered out. This doesn't happen with NeoGeo because it's declared in another source file. I'll check the behaviour in the next days but I believe it's right.
EDIT: hmmm... maybe there's a true bug. I'm compiling a new version just now. Stay tuned.