I initially posted this on the MC16 forum, but didn't get a response. I have since upgraded to MC17, and am still having the same issue. I'd be happy to help investigate or test a fix on 17 first if that's easier.
Versions affected:
16.0.181
17.0.38
Default music location:
\\server\musicarchive\wma_lossless
Auto-import locations:
\\server\musicarchive\beatport
\\server\musicarchive\hdtracks
\\server\musicarchive\other shops
\\server\musicarchive\purchased
\\server\musicarchive\wma_lossless
Portable location - sync "All Music" playlist into MP3
\\server\music\mp3
The first sync - everything completes quickly, and there are no duplicates on the share.
Next, I rip some CD's, they show up in my library, but are not "In Queue" for the portable. I click "recheck Sync", and the following happens:
Some albums are listed as "duplicate" at the top of a long list
The new albums are listed as "in queue" next
Existing albums are listed as "in queue" as well. This is the bug.
If I narrow this further and select an artist in the left pane, you can see the same album listed both as "Duplicate" and as "In Queue".
If I sync at this point, most or all of my collection will be duplicated. This wastes disk space and confuses other apps watching the mp3 folder such as Sonos and Firefly media server.
Here's an example of an album that's reported both as duplicate, and also as "In Queue"