When loading an already tagged album, and some of the tracks acoustid lookups associate them with other albums, and then they are manually moved back to the album they are already tagged with, the tracks show as red (differences) even when the tags and file naming are identical.

Steps to reproduce:

1. Find an album that has some tracks that a "Scan" acoustid lookup would attribute to a different album.

2. Save the album so that the tags and naming are "perfect" for your given album.

3. Clear all loaded files and albums

4. Enable "Ignore MBID's when loading new files" option (this isn't necessary, but enabling it makes the steps to reproduce simpler)

5. Load the same album again, letting the acoustid lookups associate the tracks with other albums.

6. Move the tracks from the "wrong" albums back to the intended album, and see that the moved tracks are shown as some shade of red indicating mismatches, even though the tags and names perfectly match that album.

Because the tracks are sometimes different shades of red (different levels of differences), I'm guessing that this is a result of comparing the tags to the albums the tracks were moved from rather than to the album they have been moved to.