A Double-Up Contest is where you can win double your entry fee. This contest type will pay out nearly half of the participants.
View this visual example below.
A Double Up Contest pays nearly ½ of the entrants out in the contest. In a Double Up Contest, the number of winning places will be clearly labeled, and players who finish in a prize-winning place split the winnings evenly, doubling up their entry fee.
As an example only: You enter an NFL $25 Double Up Contest, pay an entry fee of $25, and submit a lineup. This Double Up Contest allows a total of 3218 other players to join. This contest pays out $50.00 to players who make it to the position of 1st to 1400th. If your lineup makes it to the position of 1st to 1400th within the contest, you will win the prize payout of $50.00.
The green G () stands for Guaranteed Prize Pool. Contests with guaranteed prize pools will run even if the contest doesn't fill, and the entirety of the prize pool will still be awarded to the winning players.
It depends on the contest. If a Double Up Contest allows for multiple entries to the contest, you will see the multi-entry () icon in the contest details.