Gallery is displaying three, sometimes even four copies of the same file - why?
Though it's not the identical situation, the solution which worked out for I'm seeing duplicated images and videos on Gallery might apply here as well:


Go to Settings&rarr;Apps&rarr;Manage Apps
Select the "All Apps" tab
Find the Gallery app, open its entry, tap "clear cache"
Do the same for the Media Storage app
Have the Media Scanner running again. This can be triggered by either


a reboot of the device (ugh!)
unmounting/mounting the external SDCard if any (hm...)
attach the device to your PC via USB, optionally copy some file to it, detach it again (ok...)
for repeated use, take a look at apps like e.g. Rescan Media, Scan Media, or SDrescan (yeah!)

Check if the duplicates are gone. If not, repeat everything, but this time additionally select to "delete data"