The problem is that in 2008’s release some disks are very different from 2004’s release. Different performers, different number of tracks etc. It starts with the disk #1: in 2004’s release there were 7 tracks recorded in 1978, in 2008’s release there are 18 tracks recorded in 2006. Currently 2008’s release shows the same media for disk #1 as the 2004’s release, but that is wrong.
Some other disks in 2008 vs. 2004 releases indeed share the same media. I have a physical copy of the 2008’s release, so I could easy check disk IDs, audio fingerprints etc.
What is the right way to clean up the mess? Should the wrongly assigned media (CDs) be completely removed from 2008’s release and replaced with new media?