Redownloaded some sets over and over wondering what the heck was wrong with all my crc32/size mismatches, then checked out the sources and noted that MAME is now putting in identically named but different crc32 roms in parent/clone sets. In other words, rendering merged sets completely obsolete and unusable. No warning for ClrMame or that I can find.

When on earth did this happen and WHY wreak something that has worked for YEARS?

Edit: See that many people having this problem, also that ClrMAME is supposed to remove the parent/clone relationship for these but doesn't do so for me (and I looked in Options...).

Anyway, I suppose it's time to go to split merged... I sure hope it works, and I don't have to go to full merged which would be a goddamn disaster.