The problem is you are getting multiple collisions per Nondestsolid. Not sure why, but adding an extra flag to indicate when the collision has already been processed seems to fix the problem.
Edit: actually I think it may be because you change the animation to "land". This then resets the collision property, and it 'collides' again. That makes some sense to me.
But if it will only activates when "land" is playing then it shouldn't matter right?
I set it up that way so it wouldn't activate the other coins that I was throwing but I guess I could make it spawn another object that spawns the random event.