While I don't have the $150,000 for the Phantom-Flex camera to confirm it, I think I know why some people double tap heavy recoiling double-action revolvers.
The shooter pulls the trigger. The gun fires and recoils. The recoil impulse is strong enough to deform the shooter's grip and let the trigger reset. This happens too quickly for the shooter to relax their finger, so when the recoil impulse is finished, the finger closes again to get a second shot.
The reason you don't get a triple is the finger finally gets the relax command about this time.
The shooter pulls the trigger. The gun fires and recoils. The recoil impulse is strong enough to deform the shooter's grip and let the trigger reset. This happens too quickly for the shooter to relax their finger, so when the recoil impulse is finished, the finger closes again to get a second shot.
The reason you don't get a triple is the finger finally gets the relax command about this time.
