Originally Posted by sendittoken
Why in hell would anyone want to run a showdown twice. The idea in poker is to make money, and giving away half or more at the end is stupid.
Mostly you do it to lower variance - either that appeals to you or it doesn't.
Why would you want to do it when you're ahead? Obviously because lowering variance appeals to you. But you might also do it because you want people to give you
the option to run it twice when you get your money in and find out you're behind.
There's a few things in live poker that people let happen not necessarily because they're best for them in that particular hand but because they're best for the game as a whole.
Live poker isn't like online, there aren't endless tables running around the clock. If you think something is a little bit -EV in a given hand but it'll encourage a bad player to stay at the table or to spew more of their money away then it's often worth it to take that EV hit. Straddling can work that way - having the last action preflop doesn't really make a blind raise UTG worth it, but encouraging other players to do the same so there's more money in the pot when you're in position or encouraging the game as a whole to loosen up can be very positive.
Running the board twice can be the same way. If a fish wants to run it twice maybe you let him and hope to keep him in the game for a good while longer.