No to the spare question. Even if bowling two handed, which is legal, there is still a predominant hand. Since most bowlers are right handed, the ball will lay in the right hand, supported by the left. Much like everybody else, they just maintain contact with both hands until release and spin the ball out of their hands. That is what I have seen, anyway. We did have to warn a young man about switching and throwing the 10 pin by spinning the ball the opposite direction once upon a time. If he could have held it normal and thrown a back-up ball it would have been OK, but not the way he was doing it. Which was to reverse the whole procedure mentioned above.
