l have a Peugeot 206 GLX 1.4 and with my key fob l can lock and unlock my car. When l press the lock button, you hear the doors locking. Recently l pressed it to lock it, then a second later pressing lock again and you hear another door locking sound.
Any ideas why when l press it a second time l hear it lock again? What is it doing differently?

Thanks in advance

The second press of the button activates the car is deadlocks.