It is fairly common for at least one or two folks to have a spare ticket. The unwritten rule of thumb is ticket sales are for the amount printed on the ticket. I have seen an attempted scalp go down and, shall we say, people who had the ability to make it happen told the seller he had two choices. 1) Sell the extra ticket at face value and enjoy the show. 2) Lose all his tickets and go home now. Gotta love it when they get to make their own choice!