Just a thought. I had a wacky problem several years ago on win xp. My desktop icons would replicate giving me 2-4 copies. Made a mess with 50 or more extra icons. Only did this 3 times I think. Turned out to be an intermittent short in the keyboard. When I used a certain key combo including the shift key it must have sent some strange signal back and just moving the mouse after that caused the problem. Replaced the keyboard, problem gone.
i5 3570k, ASRock z77 Extreme 4, 8 Gb Ripjaws 1600, Antec 430w psu, HVR 1600 tv tuner, custom case- marble top, oak face. Carver & DCM Time Window sound system. Mint 14 KDE.