Or allow them to specify how much they want to play for. Let's say you have a heads up hand between two players, each with $200 in front of them and they are both all in. That's $400+ in the middle but you if they agree to cut down variance they could agree to just play for $150 instead and take the rest back.
I know they do this on High Stakes Poker, but I personally hate this, and here's why:
Player 1 calls.
Player 2 (Player 1's brother) calls.
Player 3 raises.
Player 1 goes all in.
Player 2 reraises all in.
Player 3 gets out of the way.
Players 1 and 2 agree to take their money back and just play for Player 3's money and the blinds.