Heard about this puzzle recently but couldn't come up with OR google up an answer.  Seems like an old puzzle and even a fake one ... though hoping somebody who's seen this or a variant can shed some light.

A con artist with no chess experience beyond basic rules challenges a GM to two chess games simultaneously ... one as White and one as Black.  The GM must move within 5 minutes if it's his move on either board, while the con artist has  no such time restriction.

If the con artist can tie the score 1-1, the GM pays him 50 to 1. The GM "surprisingly" agrees ... and notices that the con artist has started to mirror the GM's moves as White from the first game into his own game as White and likewise for Black.

 Spectators realized that given that the GM cannot stall (5 min / move restriction), regardless of whether he  wins, throws either of the games or tries to draw it, the result is still 1-1!

Was the GM suckered or could he find a way out of this con? If so, How?

( Is there something I'm missing or is this a fake/spurious problem?)

he could force a seemingly drawn endgame, agree a draw on one board and then beat him on the other one?

Hmm... I gave some thought into this, even played 2 games with this setup etc. and couldn't figure a way out.

The opponent would reject the offer.

why would he reject it? if he believes it is drawn on both boards then he would accept the offer (so thats 0.5-0.5) thinking that he can get a draw on the other board giving him the 1-1 he requires

Let's assume he's not an idiot. He would wait until 3 fold repetition or 50 move rule.

No, because presumably he's smart enough to know that accepting the draw comes with this risk and that it's an unnecessary one to take.

Schmidlap Maneuver?

Given that the con artist has no time restriction at all the GM can't just play sufficiently fast on one game to get ahead by two moves thus giving him an opportunity to take the two games down separate lines (the con artist would just wait out time on the first board until the GM was forced to move on the second board).

I'm guessing some dirty tricks like after reaching a position before the 3rd repeating move, GM secretly calls the arbiter and claims the 3 fold repetition in one game like the rules enforce, while the opponent doesn't realize the game ended in a draw on this manner and makes the same move in the other board without claiming the draw, and the GM steps out of further repetition possibilities and finishes him off.

But of course this is not a good solution, just pushing it. I can't think of anything else. Playing around with 50 move rule doesn't work either, because it's always the GM that has to make the first move in a given position.

OH WAIT

I think I found it: He forces a draw in one game and immediately resigns the other before the opponent could make the same move, thus escaping equality by losing.

Or he could just resign both simultaneously, or timeout on one and resign the other.

good

I'm thinking the puzzle implicitly stated that the con artist could score 1-1 at the very LEAST, as opposed to precisely a 1-1 score. So double resignation doesn't seem to be a fit. ... he could just resign both games at the beginning!

Does the GM lose the bet if the final score is 0-2? Could he lose the first game, and then, instead of playing the winning move, concede the second? That way, the score is not 1-1, but 0-2. Not sure how you would do it, but maybe there's a way . . . Ooops - just thought of it. Wait until it's his move on both boards, and then tip his king on both simultaneously. Well - maybe that would not work, if the con artist was clever enough to never let it be the GM's move on both boards . . .

Hmmm. I assumed double resignation is not possible, and as soon as he resigns one game, the opponent would do the same on the other. So I thought he would need to draw one and then resign the other.

So he has to win the match you say... Good luck to our fellow GM in that case.

yeah, kind of steering the puzzle to realm of the fake.  It's either take the puzzle verbatim and double-resign or call this a supreme waste of time :)

On this curious note, how does this not happen in a Simul? Does the GM only play one color?

Yes .

"If the con artist can tie the score 1-1, the GM pays him 50 to 1"

Just break equality, double resign.

Or bring it down to a stalemate move, play the stalemate move on one board and resign the other.