Queing to enter the North Stand Gate 6 yesterday I noticed a number of people getting to the front of the queue to enter a turnstyle before turning around, leaving the queue and then going to join the queue for the next turnstyle. It seemed they had "friends" already in the ground advising them whether, ot not, to come in at any given time.
I suspect they were trying to enter the turnstyles on "Concession" member cards and trying to avoid being spotted by stewards/officials inside the concourse.