Lasz said:
It's probably not even really ghosting, but just stuff in the shadow that's behind r2d2 that somewhat looks like ghosting, but isn't.
Here's a clearer picture:
http://www.jedi1.net/images/1600/ANH-Creatures-03176-1600.jpg
I can still see it in this pic as well. The "ghosting" follows R2's shoulder joints on both sides.