Music, purchased songs and unwanted movpkg format

In order to keep a copy of all my music ,I downloaded from iCloud all Matched and Purchased songs.

Unfortunately some of the Purchased songs come in movpkg format and go in the folder

Music/Music/Media/Apple\ Music 

and NOT in the folder

Music/Music/Media/Music

Some albums are even randomly split between the two folders.

The result is that copying the Music/Music/Media/Music folder to an external disk results in an incomplete library.

The movpkg format cannot be played (cannot even be opened) from outside Music.app

Is it possible to avoid such unfortunate behaviour ?