When I minimize a fullscreen program, which I do with Windows key instead of alt-tab, sometimes the icons for my docked programs are screwed up and have the icon for a different program in the dock.
Took a screenshot showing the problem, the program with 2 instances open is actually Chrome and not Spotify:
Sometimes minimizing a full screen program again will fix it, sometimes that just recreates the problem in a different fashion. It seems pretty random when it happens and can also happen when fullscreen programs crash.
