Drap and drop copying

I often select multiple images in order that I can manipulate them. Occasionaly, I will accidently move the mouse which will generate a load of "Copy of" images. Which I don't need.
Is there a way to turn this off so that I don't end up with un-necessary multiple images?
Thanx
Is there a way to turn this off so that I don't end up with un-necessary multiple images?
Thanx