This may also be caused by the same thing that causes duplicate music files. The only way I was able to avoid that was to remove the SD card from the phone, plug the SD card directly into the computer, move the files to the SD card, then put the SD card back into the phone. So delete the images (or just reformat the card if nothing else of importance is on there) and try this method to see if that works or not. If this works, then supposedly Microsoft is aware of this. Hopefully will be fixed in next OS upgrade. If this does not work, then as above states maybe try a factory reset.