Hi. I too have found Musicbrainz getting multi CD sets wrong and identifying the 2nd disc the same as the 1st etc.
My work-around with multi-CD sets has always been:
1. After ripping the 1st CD of a set, IMMEDIATELY rename it by adding something like 'Cd1' or '1st CD' at the end of its album name. In this way, if the 2nd CD is identically named to the 1st in the database, the 2 albums won't get confused with each other or amalgamated as the poor b2 tries to make sense of it all.
2. Then, when the whole set is ripped, manually edit artist, album & track names in the UI if necessary - it only takes a few minutes to do this.
OK, this isn't quite the fully automated process we'd all like it to be, but it works and the correct music correctly labelled ends up on my b2.
Suggestion to Martin & the crew - when ripping, the lower left hand window of the UI shows the album name choices. Is it possible in some way to also show the track info that any given choice contains? Usually there are a number of valid choices for a given album & all you can do is choose one at random and hope for the best! And often you find that your particular choice was entered by someone with OCD who insists on adding to the basic track name lots more info in brackets - such as the names of every artist playing, the location and date of the recording, the album serial number etc. etc. Aaaargh!! All this then has to be edited out to get a correct and concise track name displayed when it's playing.
On the plus side, at least this excess of info gives us something to do whilst self-isolating from this media-over-hyped Coronavirus thing.