Well, yes and no. The release is determined by a combination of barcode, catalog number, release country and date, etc. So there should not be a case of a Release containing multiple versions of a track, as that would make a different Release, but the same Release Group.
I just worked on a release like this, where the original release had the original recording and a year later, there was a re-issue with a replacement version of a recording on it. So the releases are the same except the one recording, one is original album version and the other is a radio edit, they being about 20 seconds in time different.
Now, where the issue is, trying to work off of your words, is that a Recording can be used on different Releases, giving that Recording multiple potential Disc IDs to associate with. Also, this could be a digital release where there is no disc ID at all. On digital, we can also have FLAC, MP3, AAC, etc which I do not know if they will product different acoustIDs or not.
But where the issue I discuss here shows is that a Recording is often seen in the database with more than one acoustID. Why they are different, I Cannot say, but speculate. Maybe it is a different encoder for digital, maybe someone is submitting wrong/bad data, different disc id, etc. So, lets say that I lookup a digital release. I see my acoustIDs that are calculated and I see one that differs. There are 100 with ID A and 3 with ID B. This can raise a flag to me to check the recording and make sure it is in fact correct. With iTunes for example, there are many examples of a recording being titled “My Sample Song” when in reality is is “My Sample Song (My Remix)”. So when I look, I am thinking I am looking at the non remix, but it is remix. The acoust ID can tell me there is a difference here, and if it is just a list of 2 IDs, it is not showing me the same. Does this make sense?
So I could then look and see that acoustID 12345 is used here _____ 100 times and acoustID 54321 is used 3 times here _____. I may then be able to see what I really have and avoid a crossing of recordings that are actually different. So like the ripping I mentioned above, there I can see if my CD rips a little off compared to others, which is actually quite common and possible. The difference there might be nothing as I could be correct, it is just a visual confirmation / warning of my results. If I rip with 100 confirmations, there is good chance all is good. If I rip with 2, that is a lower confidence factor.