It was discovered by many Redditors an interesting BUG while catching Pokemon with curved throws, and it’s called the “Double Bounce Catch.”
The purpose of the throw is to perform a difficult stunt throw in which the Pokeball bounces from the Pokemon, and lands right back on it. The newest throw revolves around a bouncing Poke Ball and it is said to be rare and almost impossible.
The conditions for this bug to work are that the selected Pokemon has to be finishing the attack animation, but right before it finishes, you need to hit him with a curved throw at the right angle. This needs to be done in this way in order for the ball to bounce and hit the Pokemon again, as GoHub announced on their website.