Second river is dealt?

I saw this on Poker After Dark:

Board is dealt through the turn and at that time 3 players are in the hand and they all are all in.

I can't remember the hand exactly but effectually it is this,
Player 1 89o
Player 2 89o
Player 3 4d5d

Flop is 3 6d 7 one diamond turn is td
So now all players are all in, two players have nut straight and player 3 is on a flush draw. At some point there is the agreement to deal two rivers.

I have never heard of this. Could someone explain it to me? When is the deal made and what is in it for each player? Where is the advantage and when is it allowed?

as a dealer i have never haerd of this....ever ...sounds to me like it was a couple of first graders making up the rules as they go lol

Must have been on one of the cash game episodes. Basically, on these televised cash games, as long as everyone in the pot agrees, they can do what they want. They can split the pot in any fractions they want, they can deal multiple boards; whatever.

With multiple boards, the pot is divided equally. So, if they dealt 2 rivers, the person with the best hand after the 1st one takes half the pot, and the best hand after the 2nd one takes the other half. (possibly further split in a 3-way pot)

It's usually done to reduce variance and act as an insurance against someone drawing out on you.

Haven't seen it on PAD that much, but it isn't at all uncommon on High Stakes Poker, especially if Antonio Esfandiari or Daniel Negreanu are involved in the hand. Requires the agreement of all players in the pot. Way it works, as I understand it, is if Player 1 (in this case, Players 1 and 2) win with the first River and Player 2 (in this case, Player 3) wins with the second river or vice versa, they chop the pot. However, if Player 1 wins with both rivers, he/she gets the pot and vice versa.

You have to remember, these guys add all kinds of variations into their games; i.e. the 2-7 rule, where anyone with 2-7 in the hole who wins the pot gets $500 from each of the other players; straddles; and "prop' side bets, so you are likely to see them do things you won't see in any casino or in online play.

Most of the other questions have been answered above, so I'll just address this part.

I don't know that you'd call it an 'advantage' as such.

For the player that's behind, it gives them additional chances to catch the cards they need to finish with at least some of the pot. For the player that's ahead, it reduces the chances of one suckout taking all their money: they may have slightly reduced their chances of winning the entire pot, but they've greatly increased their chances of taking at least some of it.

So it's mostly intended to reduce variance. The more times you run the same situation, the closer in theory you get to the statistical norm for that situation. If a hand was 80% to win when the money went in, it still has 80% equity in the total pot (it can be affected slightly depending on the number of times it's run and whether it's done preflop, on the flop or on the turn, but it'll still be in the same ballpark) and in the long run can expect to take the money 80% of the time.

You can only really do it in cash games, as the only parties affected by it are those in the pot and it's (relatively) easy to get consensus on whether it's going to be allowed for this hand and how many times to run it. In a tournament, in theory everyone at the table (or indeed in the field) can be affected by the outcome and getting agreement would be nigh impossible, so it's just not done.

If you're in a casino, it's usually only the higher stakes games that allow running boards multiple times.

That sounds cool, maybe I will try that at my next cash game when the luckbox ace rag beats me on the river. A second river could change everything. Then I'll try talking them into giving me a third whole card.

There is no advantage. The odds remain the same, and it's simply a way to reduce variance a bit. Generally it'll happen when players have quite a lot of money in play, and someone has a small edge. The player in the lead is happy to take two because if he gets sucked out on, then he has another shot to get half the pot. The player behind likes it because he gets two tries at hitting the suckout and getting his half of the pot.

two rivers... wow... never heard of that before. But, if its a live game and people all agree to whatever the proposal is... I guess they can do what ever they want to lol!