I believe back in the day you could only attach DiscID's to release groups, and when that changed each ID got assigned to every release in the release group. So as well as not having the edit history, you wouldn't necessarily find out more about the specific edition it was intended for (unless you could get in touch with the editor, but with older additions it's unfortunately not possible). Possibly because old DiscID's were imported from another service originally/migrated over, anybody?
Quite often I remove ID's like this, when data is getting confused, especially when it's impossible to ascertain what edition they actually belong to, and the only way to find out is to have someone eventually add the DiscID to the correct release...
In this case though the tracklists are very different though so you can't really confuse the two.
Sorry for rambling