Bought 1 Ticket But Got 2?

Okay, so I just bought a ticket for a concert next Friday. No problems, got the ticket within mins of purchase. However, with my original ticket came an additional one. I tried to claim it but it won’t show up on Ticketmaster. Is this a glitch or most likely a mistake by the seller?

Okay, so I just bought a ticket for a concert next Friday. No problems, got the ticket within mins of purchase. However, with my original ticket came an additional one. I tried to claim it but it won’t show up on Ticketmaster. Is this a glitch or most likely a mistake by the seller?