The only time they will both run is:
Take-off (a/c in ground mode, take-off flaps selected AND ground speed > 80knots).
Undercarriage retraction.
Autoslat demand.
The reason for them both to run is to ensure enough hyd. press. and flow for the rudder (TAC) in the event of an engine failure.
Both ADP's go off after 10secs. in the air.