I’ve just added a few dozen classical albums and found many that have the same barcode as different albums in Core. Publishers appear to “recycle” the same barcode for multiple album releases. So the incorrect album is often presented as the “barcode match”.
Searching on Catalog Nr. can help, but not all Core albums have this recorded in the database, apparently. Also I don’t know if Update From Core looks at both the barcode (duplicate matches) AND Catalog Nr. (at least different for the same barcode number – IF it’s there at all). So far, it’s replaced several of my existing albums with the wrong album match.
I can workaround by changing Title and Artist and Artwork for affected albums, but will an Update From Core undo all my hard work editing the affected albums? And there are plenty of them, just in my tiny selection of the world’s classical album releases.