When MediaMonkey scans a directory, it only adds files if they don't match an existing filename, otherwise it just updates the tracks with any changes to the track properties that exist in the tags. Under certain scenarios you can end up with duplicates in the Library:
- You actually have multiple files of the same track
- You moved/renamed files outside of MediaMonkey and scanned the new files in. MediaMonkey will see them as a separate new file.
- To prevent this use MediaMonkey to move/rename the files or use Folder Monitoring. Dead Links will show the old copies of the moved/renamed files. Deleting can be done from there, but this removes the files from any Playlists they're associated with as well as removing its Play History.
- You used the Update Location of Files in Database Addon, but scanned files before using it
- If you use it, make sure you have Folder Monitoring disabled before you've used it. Otherwise MediaMonkey ends up scanning the files from the working location and then the Addon fixes the non-working files resulting in 2 entries for each file in the Library.
- You replaced the hard drive or moved to a new PC and scanned the files in again.
- You used a Mapped Drive for your network files and rescanned it after the DriveID changed
- Windows is known to occasionally change the DriveID for Mapped Drives. We recommend using the UNC Path for the network Location instead of a Mapped Drive to prevent this.
- You scanned a location that includes the trashcan
- This can happen for NAS devices which can end up with files in the recycle bin when they're edited. To prevent this make sure the media files are not in a location that includes the trashcan (which often is in the root). A sub-folder, and only selecting it for scanning, for your media files will solve this.
For duplicate management please see: Can MediaMonkey help me find and delete duplicate tracks?