A couple years ago my Dad was supposed to be flying into Denver for a hunting trip. He checked into an airport in about an hour from where we live. Checked his bags, got his boarding pass, and headed to the security gate. He gave the boarding pass to the guy checking ID's at the line and security guy looked back and said "Enjoy Boston". My Dad looked at him confused, and said, no I'm going to Denver. The security guy said, no your boarding pass says Boston.
Dad looked down and sure enough it was for Boston. He went back to the travel counter and started asking questions. They looked up his info, confirmed his first name, last name, middle initial and date of birth. Everything was right. They still had him down for Boston. Dad insisted that it was not right and he was going to Denver. They started digging a little deeper and finally asked him his address. The counter person looked confused and said "But you really are this person right?" And Dad said yes, but I live at this address.
So they dug a little more and finally found another person of the same name and date of birth with the address that matched Dad's.
He happened to be flying on the same day, on the same airline, in the same airport as another person that had the same exact name and date of birth as him.