A closure sequence controller for a pair of first and second door leaves pivotable with respect to a door frame includes an elongate guide rail for mounting to the door frame, a first elongate sliding bar positioned in the guide rail and functionally connected to the first door leaf in a manner such that the first sliding bar moves in response to pivotal movement of the first door leaf relative to the door frame, and a sequence control unit installed in the guide rail and functionally connected to the first sliding bar. The sequence control unit includes a lock body structure defining a chamber through which the first sliding bar extends and having a guiding surface that is inclined with respect to the first sliding bar. A blocking member is located in the chamber and movable therein longitudinally of the first sliding bar. A biasing element urges the blocking member in a direction towards a position in which the blocking member is clamped tightly against the first sliding bar and prevents closing of the first door leaf.