Ok, well, HOM happens when there's nothing behind something for the system to draw. So it draws the location of something in one place and then when it moves on the screen, it never bothers drawing over where it just was, leaving it in place.
The funny part is there doesn't seem to be any reason for it to occur on your game because you're not turning the backdrop off anywhere. But theory doesn't matter as much as what actually happens.
There's more information on how it works at wikipedia
http://en.wikipedia.org/wiki/Hall_of_mirrors_effect
The latest version of anything doesn't necessarily mean it's better. Updates always include new code. New code can introduce new bugs. Some people wait before upgrading or simply refuse to upgrade if there doesn't seem to be anything wrong with what they have. The old adage "if it ain't broke, don't fix it"
No matter where you are... everyone is always connected.