The issue here is that AllMusic is saying that all those people are the Primary Artist on this album.
Our current product design handles this well in the vast majority of cases, including albums that genuinely have two main performers, like this one for example. Unfortunately, we’ve seen a few examples of albums where AllMusic seems to designate way more people this way than we would expect.
We’re doing some analysis on this to see if the problem is widespread enough to necessitate a change in the product. For now this seems to only affect a few albums, so I would encourage everyone to submit corrections directly through the album’s page on the AllMusic site for now. It’s pretty easy, and our experience is that they tend to fix issues quickly, which then filter down to Roon.
Thanks all!