Remember reading many many years ago that it was entirely possible no two passengers paid the same fare on some flights.
(arranging a train trip a couple of years ago, friend texted to say he was up for it while I was sitting in a park - I checked train times and there was some super cheap off peak deal available on one service, texted to say shall we aim for that? By the time he replied yes, I was walking - got home, tried to book my ticket - all gone, I paid the next best price while my mate got the cheaper deal!)