Last night I was playing in the MDS MEGA freeroll on ACR. A player started the hand with around 300, went all in, and then won a 677 pot.
That player then started the next hand with 3677, as if he double re-bought. The player
was weak and didn't get close to the money, so it seems unlikely to be cheating...
When a MDS MEGA freeroll ($0 buy-in, for example) starts and the first hand is dealt, once the dealer button is shown on the table the game is "now live". At ANY time your stack is AT or below the 3000 starting chip stack (again, $0 buy-in for example) ANYONE at the table can click the re-buy button in the upper right corner of the table at any time and top their chip stack with a SINGLE re-buy for $.50 :flute:
Even if you don't play the first hand (and have 3000 in chips) you can still do this and at the start of the second hand your chip stack will top off giving you a stack of 6000 chips.
I've been playing on Winning Poker Network skins (Black Chip Poker mainly) for a good 4-5 years now and it's always been like that; just be happy they don't allow the double re-buy option for topping off their stack.
Besides, it's effective to use when you get an over aggressive donk on the table that's known to shove all in pre-flop on the first hand with garbage cards if they win the hand and then challenge them on the second to shut them down, and even sometimes fun for a third hand (though it could be costly if he is on a donkey roll), if you get dealt a prime starting hand.