David21,
After reading your question again, I think both players showed each other their cards before folding. That might change my original answer. TDA #18 Asking To See A Hand does not address this situation. Most poker players are familiar with "show one, show all" and the TDA does address it in #59 No Disclosure. Maybe it should be noted in #18, also.
I would certainly allow the floor to determine whether the cards should be revealed, especially if collusion or chip dumping is suspected. Your situation does seem strange because there are so many easier ways for Player A to "dump" his chips to Player B, without raising suspicion.
Having the floor insist that both hands be tabled would be the best way to discourage players from such actions.
Good question that could have a quick fix at the upcoming summit.