Item frame duplication bug

For some reason, item frames seem to duplicate upon logging off and back in. However, it doesn't seem to duplicate for every world. It may have something to do with the superflat preset I was using. For reference, the preset I used was:
2;7,60x1,5x3,2;3;

It was creative mode with generate structures set to off.

Steps to reproduce:
1. Place an item frame on a block, and put an item in the item frame
2. Save & quit to file
3. Load the world back up
4. Hit f3 and notice the extremely high entity count
5. Break the block that the item frame is on
6. When the item frame breaks, it will drop a lot of item frames as well as the item that was put inside of it (764 to be exact)