One of my End maps started showing a portion of the Overworld. 

A copy of the map was on the wall when I first noticed it. I had flown over the Overworld chunks displayed before I saw the map, but I when I tried to add to the area Overworld area I could not. 

The wrong portions of the map showed up on the wall as well as in either hand. They also persisted through quitting to desktop and reloading the game.