One time I put my money in the machine and it gave me two chocolate bars instead of one, and it gave me my money back.
But the money was in all quarters, so it weighed my pants down the whole way home. And the extra bar was melted in my pocket by the summer heat after I had opened it. So when I got home, I had a messy ball of chocolate quarters in my pocket.
Sometimes it's better to just get the one chocolate bar.