I frequently see an orchestra given twice for performance (see below). I can fix that by using the Track Editor to remove one instance (often the orchestra appears as orchestra and as primary artist). But it shouldn’t be necessary.
I think this happens when the artist was already in the library (from file tags) but not identified and later after a successful identification of an album the artist couldn’t get mapped to what Roon now knows. If you search for the CSO, how many different results do you get from your library? The Roon IDed entries should have a picture of the orchestra, unidentified entries probably have not.
If you click on both of the links do they take you to the same exact artist page? Or are they slightly different?
In a search for “Chicago Symphony Orchestra,” there are 2 hits (ignoring the hit for orchestra and chorus), as shown below. It’s hard to see in the screenshot, but the first hit has a picture of an orchestra, and the second, a blank picture.
Clicking on the second (blank), there are 3 associated albums; on the first (non-blank), there are 20 associated albums. There is no overlap in the sets of albums. [Update: See below.]
Thus, there are 2 distinct CSO entries, as you (and Dylan) speculated. The existence of 2 entries presumably is the reason that CSO, for example, sometimes appears twice for performance.
There are indeed 2 entries. I’m not clear about the overlap or lack of overlap.
If both CSO entries have additional metadata - especially links which you cannot add yourself - it would indicate that Roon knows about two CSOs and should therefore try to unite the orchestras in its cloud metadata.
Today I noticed that in a number of albums, Orpheus Chamber Orchestra appears twice, once as orchestra and once as primary artist. In all these instances, the picture accompanying the two roles was the same: Nothing like a good picture and a picture of “unknown” that I’ve seen elsewhere. That suggests that Roon isn’t always using 2 distinct performer instances.
Found another: In Nigel Kennedy’s “Violin Concertos” by Mendelssohn, Bruch and Schubert (https://www.allmusic.com/album/mendelssohn-violin-concerto-bruch-violin-concerto-no-1-schubert-rondo-mw0001388509), English Chamber Orchestra appears as orchestra and as primary artist. Clicking on the first leads to a presentation with a photograph, essay, “From England, Formed 1948” and 6 main albums; on the second, photograph, no essay, “From United Kingdom, Formed 1960” and 3 main albums. So Roon thinks there are 2 instances. This looks like some database glitch.
Pictures of the 2 instances:
One comes from allmusic/Rovi (see: https://www.allmusic.com/artist/english-chamber-orchestra-mn0000803128/biography), the other from musicbrainz (see: https://musicbrainz.org/artist/8c936585-f1e5-4729-9402-98f319d265b0).
But from the data at musicbrainz (and wikipedia) I can also see why this may not be so simple solve: when was the ECO founded? Should Roon decide? Metadata sure ain’t fun (anymore).