Another ruling question (theoretical)

[matt2500]

Here's one I've never encountered. A buddy of mine was playing in a small $35 tournament with around 25 players.

Eleventh-place goes bust, the players redraw for seats at the final table, and go on a five-minute break. He's seated to the right of another regular in these tournaments.

They return from break, he takes his seat, and both he and the guy to his right fold their hands. After the hand is played out, guy to his right says, 'Hey, I don't have this many chips.' It turns out he had taken my buddy's seat, and my buddy his.

If either, or both, had actually played the hands they were dealt, what would be a ruling? Obviously, they would be playing cards that they should not have seen, with chips that aren't theirs. If one were to get into an all-in situation, the number of chips they'd be playing would be wrong.

This one had us both stumped.