Hello, the situation you mentioned has also happened to me. It is a system problem. This problem may be a system error caused by GDR update or some improper operation of the mobile phone.

First, follow the sequence of Settings - Phone Storage - SD Card - Remove SD Card to safely remove the memory card.

Next, use a card reader to connect the memory card to the computer.

Then, open the memory card on your computer, find the "WPSystem" folder in the root directory, and delete it! Yes, that’s right, only delete the WPSystem folder under the root directory

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Finally, safely remove the memory card from your computer and put it into your phone. If the option to store music pictures on the SD card appears, select Yes.

Now, open the mobile music playlist, picture browser, and video playlist, and the files will be arranged neatly one by one without duplication.

Note: After reinstalling the memory card on the phone, the list of music, pictures, and videos may not appear immediately. This depends on the number of files in the memory card. It doesn’t matter. Wait patiently for two minutes before opening it again. , no more duplicates in the list.

If it doesn’t work, just reset the phone. This is how I solved it. Remember to make a backup before resetting.

WP8 enthusiasts will give you answers, hope it helps To you.