> hmm....the rebuilder swtich 'rebuild nodumps' is disabled and not checked, isnt
> it?
>
> Hmm..can't repeat it here....dropped some nodump files and they get not created.
>
> Maybe you can zip up your used *.cmp + *.dat file + cmpro.ini + the rebuilt
> nodump and mail it to me?
>
>
> Roman Scherzer

After some further check I found that the file with this problem is chinagat.zip, which I believe is a special case. Files a12, a13, a14, and a15 are marked as "nodump" in sets chinagat and saiyugou, but are valid ROMs in sets saiyugb1 and saiyugb2.

However, this problem didn't happen before 3.108a, so I'm still not sure if this is my problem or a newly introduced bug. Anyway, some info of my settings:

"Merge Options" in Rebuilder: Merged Sets
"You prefer" in Scanner: Merged Sets
Questions answered during MAME listxml and dat generation: I believe I clicked "OK TO ALL", but I'm not quite sure.

Procedure to reproduce this issue:
My chinagat.zip contains all ROM files necessary for all the 4 sets. The Rebuilder would rebuild everything into the collection, but the Scanner would report the 4 files as unneeded for "chinagat" set.