Originally Posted by Ahmed_Al_Gendy
thanks for responding nkk71 but I didn't quiet understand what you said cuz I'm still beginner in android so if you can simplify I would be grateful
As of 4.2 the file structure was changed. So before the update all your data was in a folder /data/media and now all the data should be in /data/media/0
The folders you are showing in your picture "0" and "legacy" actually are just links to the same primary folder which is /data/media/0. So even though it seems that there are two separate folders, it's actually the same one with the same contents. no duplicates.
During the update it MAY have happened that the files were copied to the new location (/data/media/0) BUT also remained in the old location (/data/media).
So in order to be able to see if there are any leftovers you would need a file explorer, such as ES File Explorer, and enable ROOT access to see the files in /data/media. If you do not enable ROOT access then the files won't show up in /data/media because they're hidden away from non superuser.
You are rooted right? What ROM are you running?
Oh, just a thought came to mind, what Music app are you using? Can you find out from which folders it's creating the library.