Merge Rather Than Delete
From MusicBrainz Wiki
It's usually best to merge duplicate entities (releases, release groups, recordings, etc.) instead of deleting them.
Deleting entities has two kinds of bad effects on the database:
- The MusicBrainz identifiers that have been referenced anywhere (tagged files, links to MusicBrainz from other sites) will become invalid when the entity is deleted. When merging it, however, the old identifiers will forward to the entity it is merged into.
- Even if there's no useful data attached to the entity when you enter the edit, it's possible that someone may enter it before your removal is approved. If so, the recently added data will be lost.