> different name to the parent, CMP ignores the merge.

ClrMamePro doesn't use the "merge" tags at all. It creates its own parent/clone rom relationships. It uses a much more stricter and more valid method than MAME's merge tags (besides they were too wrong too often). It doesn't matter if the hashvalues are identical, if the romnames differ, you need both files. The fact that there are double-roms (same crc, different name) is known since the first days of MAME and usually a good driver author fixes the names ;)
MAME doesn't complain because MAME's loading procedure is a mess ;) It simply looks in all sets of a parent/clone relationship and looks for a matching checksum. It doesn't care about romnames at all.

Roman Scherzer
ClrMamePro