You have two options here. The first is to ask the CM's when you go to the FP machine what show is currently be distributed. If they are currently dispensing the first show, try back later. You cannot, however, request what show to see when you get the tickets, as it is first come, first serve.
Your second option is to pay for a picnic or dining package that will allow you to request a specific showtime if for some reason you have to see the second show and not the first.