Oh, by "You can have the same corner cases with audio-only releases" I didn't mean mono/stereo releases. I rather meant a reissue, several years later, with the same band and release title, but with a completely different cover, a different label, and sometimes a remastering and/or a slight change in the track list.
It's not uncommon. Take for example an artist that eventually decides to not renew their contract with their former label, and to reissue their past releases using their own label. This is the kind of corner case I was referring to. Despite the time gap, a change in cover, a change in label and a remastering, few would create a new release group.
As for AJICO SHOW, your question is difficult, mostly because I don't read Japanese. What puzzles me is that, although there are a lot pf tracks in common, the track order differs. On the other hand, the releases have the same title and label, and above all, they refer to the same concert. In my opinion, this is the same RG.