As long as you're not mixing gas sources, just fine.
It was actually fairly common in the early-mid '90s to see players with Autocockers or Tippmann Mini-Lites run dual tanks with a vertical 3.5oz and a 20oz on bottomline. The smaller tank acted as both an expansion chamber and condensation reservoir to help keep liquid CO2 out of the gun.
ICD alleycats and puma's i believe both came stock with dual asa's as well. I could never lug that vm around the guns are heavy and then puttin 3 tanks on it.. my gawd >.< the dye stainless on it wouldnt help either
Yeah, I forgot about the Alley Cats. I've messed with them a bit. We had several at the field I modded for use as AT for OK D-Day. But you are right, they had the air intake up front and then on the rear of the reciever.