this valve comprises : a body ; a first channel for channelling the flow of a fluid ; a second channel for channelling the flow of a fluid ; a first valving element which is movable translationally in a first direction , between an open position and closed position of the or each first channel , the body fouling a first seat for the first valving element ; and a second valving element which is movable translationally in a second direction , between an open position and a closed position of the or each second channel ; the first direction and the second direction being parallel or coinciding with each other . the first valving element defines a housing for the second valving element . the first valving element forms a second seat for the second valving element .