This is a little modified (not a true double elimination). In the first 2 rounds (Ro32 and Ro16) you will have the safety net of dropping to the loser bracket. After that, if you lose in the main bracket, you're out of the tournament. This is why the finalist in the loser bracket must win twice to be champion as it makes it a bit fairer.
LOSER BRACKET: Round 1: The 16 losers of the groups will face off.
Ex in Loser Bracket Round 1 and Round 2: Round 1: UserA vs UserB Round 2: [Winner of Round 1] vs UserC (dropped from main bracket)
After that it'll be straight elimination just like the main bracket.
In the Dual Round (Ro32), there will be a chance you will play the same person twice which is normal (if you win a game then lose one, you may end up in a rematch for the tiebreaker).