Maybe there is someone who has really mastered this but I think the time you spent trying to master it could be better spent mastering a single gun.
For one, how do you do a tap-rack-bang with 2 hand guns?
How do you do a tactical reload? How do you reholster? How do you open doors or practice retention with 2 handguns?
If you shoot 75% as well single handed, and only 50% as well weak handed, you are seriously handicapping yourself by shooting a gun in your weak hand and an unsupported gun in your strong hand.
I think its pretty retarded. I understand the visiual appeal on movies but it still drives me crazy - I have no more desire to shoot two handed than I do to go buy the guns I see in movies.
When you are using one gun properly, your sight picture and they gun are "fused" and you are a little human handgun turret.
It takes time to reacquire a sight picture on another gun in another hand, focus, then do the whole OODA process and shoot, then switch back - you are inserting many unnecessary processing cycles for your brain to deal with when what you really need to do is come up with LESS for your brain to deal with - so you can loop faster and win the fight.
No offense to those who have tried it - I have tried it - I already thought it would be difficult and useless and I was shown to be right.