Can you run 2? Yes. In PCIE slots of x16, x8, x4(not recommended).
Is there a benefit? Yes, on the professional level - sorry, that's the best answer I can give because I'm not familiar with those programs.
I just know that some run multi-gpu Titan and Quadro setups for the kind of work they do.
Downside?
-Heat produced; overall higher case thermals. The top card at the very least, should be a blower type(ideal for tight spaces). A standard fan model will thermal throttle due to proximity to the bottom card.
-Overall power consumed.
-A robust power supply is a must, don't even try to cheap out here, not that anyone ever should.
-Driver support is sorely lacking. So most times, you'll have one card sitting in your motherboard doing...