A double swing gate has an active leaf and a passive leaf. The active leaf is the one you use day to day: it opens first, closes last, and carries the lock or latch. The passive leaf stays shut until you lift its drop bolt, and it carries what the active leaf closes against: the stop strip and the striker.
Which leaf is active is a site decision. It is usually the one nearest the path people walk, or the one that suits the hand of the lock. On a gate with unequal leaves the smaller leaf is often the active one, so it works as a pedestrian gate.
CAD60's double swing models let you pick the active leaf and which way the leaves open. The lock box, striker plate, drop bolt and stop strip then land on the correct leaf and face.