I was reporting a 7 person PFS table, and filled out all of the information for the first 6 players, then clicked "Add Additional Player". I then filled out the 7th player's information, and clicked "Save and Exit". I then noticed that my GM Table count went up by two. I took a look at my scenarios, and sure enough, there were two tables for that session, one with 6 players, and one with 7 players.
(I have since deleted the 6-person table session, since that was incorrect.)