You'll only need ONE 8" fan for that setup - placed at the Beginning of the chain pushing the air (That way if you have any leaks in the system - you wont be sucking dirty air to your exhaust
Also - why not butt the rooms right up next to each other and use ONE A/C ? Vent air using a cheap blower into/out of each room to exchange air !.
I actually do BOTH of these tricks in my Mother/Cloning/Veg rooms.
I cool 8 1000 watters with One 8 " 733 CFM fan no problem.
All you have to do to cool both tents is to put 2 - 6" ducts between the two tents - with a blower going in each direction to exchange air between the 2.
I have 3 rooms cooled this way with only ONE A/C in one room. This allows me to share C02 between the rooms as well. I'll put up some pics in a bit.