Some of the larger B and C stands have a centre parking line for a wide body aircraft but they also have a L and a R parking line, enabling 2 x narrow body aircraft to park there instead.

eg, gate B45, stand 545 could be used for a jetty serviced 777 departure with the aircraft parked in the centre line. Instead, 2 x A320s could be parked on 545L and 545R. One would have to be coached. The other could use the jetty.