Extra sub-albums for multi-disc album

[Servatius]

I made some more experiments which may help better to understand the reason of the problem.

When I move the top folder of the 41-disc album into a new library directory containing nothing else and configure this library directory as the only contentDir in the MinimServer configuration, the problem is gone. I only get the complete album and no extra album.

When I move a second multi-disc album into the new contentDir, the problem comes back when it uses similar ARTIST/COMPOSER tags. In my test, the second multi-disc album consists of 10 discs, again each disc in a separate subfolder, and uses the following tags:

• ALBUMARTIST not set on any of the tracks for any disc,
• ARTIST set to "Anton Bruckner" for all tracks of all discs
• ALBUM set to "Symphonies Nos. 1-9" for all tracks of all discs
• CONDUCTOR set to "Günter Wand" for all tracks of all discs
• COMPOSER set to the same value as ARTIST
  

This second multi-disc album is shown correctly and only once. The control point shows an album value of "Symphonies Nos. 1-9" and an artist value of "Anton Bruckner, Kölner Rundfunk-Sinfonie-Orchester, Günter Wand" (as I did not specify ALBUMARTIST, I get the ARTIST value). However, the existence of this multi-disc album causes the extra albums for the first multi-disc albums to reappear - but just two of them related to ARTIST/COMPOSER "Anton Bruckner". This is what I get:

• An extra album "Claudio Abbado - The Symphony Edition" with an artist value of "Anton Bruckner, Lucerne Festival Orchestra, Claudio Abbado" (which is the Artist.displayFormat value). This extra album contains only disc 26 because this is the only one with ARTIST/COMPOSER "Anton Bruckner" and ORCHESTER "Lucerne Festival Orchestra". This album appears because the same ARTIST/COMPOSER is used in the other multi-disc album.
• An extra album "Claudio Abbado - The Symphony Edition" with an artist value of "Anton Bruckner, Wiener Philharmoniker, Claudio Abbado" (which is the Artist.displayFormat value). This extra album contains discs 27 - 30 because these are the discs with the combination of ARTIST/COMPOSER "Anton Bruckner" and ORCHESTER "Wiener Philharmoniker". This album appears because the same ARTIST/COMPOSER is used in the other multi-disc album.
• The complete album "Claudio Abbado - The Symphony Edition" with an artist value of "Claudio Abbado" (which is the ALBUMARTIST value). This album exists independently on the existence of the other multi-disc album.
  

The problem is not related to having ALBUMARTIST set for the 41-disc album and having it unset for the 10-disc album. I added it on the latter via a tagUpdate file which did not change anything.

So it seems that album merging for one multi-disc album may be affected by a different multi-disc album that uses partly the same values for tags specified in Artist.displayFormat. In addition to the correct and complete first multi-disc album, extra albums with combinations of tag values from the other multi-disc album appear.

I did not test whether the first multi-disc value may be disturbed just by a single-disc album with a value for ARTIST/COMPOSER also partly used in the multi-disc album.