Howtosignalprocessing
In the Playlists section, right-click on the name of your device. Click Display duplicates. Now you can see all the duplicated tracks in your library. To delete duplicate songs on iPhone, simply select one copy of the tracks listed, right-click and select Delete from device.
Why are there 2 copies of songs on my iPhone?
iTunes or Music may create duplicates if the same content is repeatedly added from outside the media folder when it is set to make copies of anything that is added to the library, or is added from an external drive that hosts the media folder if it was offline when iTunes or Music was launched.
