For double pick weeks you need to get both correct, but you only use one mulligan if you get one or both picks wrong. Players will not be eliminated if going into a double week pick undefeated since only one mulligan is used for the week.

If you want to handle this differently (i.e. not revive a member with both picks wrong) you can manually go in and remove the mulligan that was issued under commissioner console --> Issue Mulligans.