|Description:||As I was voting on images, I accidentally pressed the "down" button instead of the "up" button on an image. I then noticed that I cannot change the vote. So, I had an idea.|
I'm not sure how the voting mechanic works, but could you make it so that, if one of the voting buttons are pressed, that button will be worth 0 and the other is worth 2 (or -2, for down) points on future presses by that user.
This would have to be updated every time that a score is changed, so that a person can't vote "up" once, then spam "down" votes (or vice-versa).