Over the years I have seen players do this in one pocket- say your opponent needs 1 ball and has a ball so deep in his hole that you can't remove it and there is a ball on the table that your opponent could make
if he had ball in hand behind the string line if you made his ball and scratched. Simply double hit the cue ball
real easy and make the ball in his pocket but don't scratch. The ball you made comes up plus one of your's- I always thought it bordered on
cheating but on the other hand I not aware of a rule against it and you're still alive!
If a guy pulls that move the best thing to do is don't call a double hit foul on him... and if he says he did double hit the cueball just say you didn't see it. Games over you win.