a|*1|*2|b|*3
Move "a" to "*1". It will look like *|a|*2|b|*3, but it's really a|a|*2|b|*3.
So if you move "b" to "*". where there is a hidden "a", your game will crash. but, you could move it *2 or *3 it'll be fine.
But, after you change the box and go back, you will see the hidden clones, and can move them around freely with out you game crashing.