If a concert is rescheduled, are new tickets with the correct date sent to you?

Or do you still use the ticket with the original date? I was looking on Craigslist for Rascal Flatt tickets who were originally scheduled for Oct 16. Now they are scheduled for Oct 1 and a person is selling tickets which lists the original date. They are listed at a really good price so I am interested. I just don't want to end up at the door not able to get in and out the $$.