Yes we have the double wave. It was created due to the standard wave to OO being received with a blank stare. So you get the other hand going until they acknowledge you. If I am taxiing by a fellow CPZ aircraft, it's my standard. I occasionally need a cold shower when we pass and I get no wave in return.

As for the standard pilot nod, I find that it's returned most of the time. Except ATL...it's 50/50 there. A cold shower follows when I get eye contact and they don't return the nod.