ASL Companion #3 (p82) :
When one unit in a stack spends movement factors for an action, such as picking up a weapon or throwing a smoke grenade, all unit in the same stack spend the same number of movement factors even though they don't participate in the action.
Differents units in the stack may spend the same movement factors on different actions, as long as they declare their actions before the movement factors are spent and any die roll is made, and the stack stays together.
Pour moi on declare avant la depense de MF que les deux squads agissent en stack, chacun lance son dé de test de Smoke, les deux on dépensée dans tous les cas 2MF quel que soit les resultats : si l'une des deux fait un 6, elle stop sont mouvement et l'autre est libre de continuer ses actions avec les MF qui lui reste.