Are these tracks located on an external drive? One of the many ways in which iTunes/Music can end up with duplicates is if it is launched when an external drive isn't attached/ready. The app then assumes all tracks are unavailable, even if the drive is then connected/wakes up. If any content is imported at this point the app will fail to recognize those items that are already part of the library, creating what I refer to as logical duplicates, multiple entries in the database to a single physical file on the drive. Deleting any of these and allowing the underlying file to be deleted will break the remaining entries, but on a Mac only when you empty the trash. Take care when cleaning up. I would recommend backing up the whole library before deduplicating so that anything deleted in error can be restored. It can pay to use the Automatically Add to Music folder to add new items to the library, or be selective when importing so that only genuinely new content is added rather than picking a higher level folder and importing everything with the assumption that existing items will be passed over.
See Duplicate songs in iTunes/Music - Apple Community for further information.
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