It sounds like apache is using a sort of hybrid departure/vortex separation.
I would ask the question what happens if, when the second departure pops up on radar, you haven't got the rquisite space between the aircraft?
And, as I think about it some more, what assurance do you have that there is enough space between the aircraft if it takes a good few secs for the aircraft to appear on radar, say if the head is a way away?