The car will only double lock if you turn the key as far as it will go in the "lock" direction. Twist the key slightly and it will lock normally. Even if you do double lock it and something is wrong with the locking system, there is a way to override it manually. Turn the key all the way in the unlock direction and pull the door handle up, with the door handle pulled up, turn the key an additional 1/4 turn to unlock the door. Somehow i think something is missing in the description of your problem tho...