Same thing happened back when I was in high school... the people who stock the candy machine put "10cents" instead of 70cents .. i found it out when i put in a dollar to get a Reese's (which was 70 cents), got back 90 cents and im like huh??! Tried again, this time with a dime and walla!!! needless to say, the school lost a lot of money, and i had a backpack full of candy woooooooo