Like many I am sure on this board....I hesitate to answer. Obviously for fear of feeling...well... stupid! But, here goes none the less.
My first inclination was to say each of the balls would depart at the same velocity no matter the weight behind the strike.
However, I am going to GUESS that the larger mass will not absorb (possible wrong term used) as much of the strike against the ball or absorb more efficiently the strike. Thus imparting more energy or transfer of it to the ball and a greater initial velocity.
Just a guess.
