if two balls of equal mass collide going the same speed what happens??

For the sake of argument we're going to assume that this is an elastic collision. Therefore, the sum of kinetic energy and momentum for the two objects will be the same before and after the collision. So, if 2 objects of the same mass and speed collide head on in an elastic collision, their direction will be reversed and their speed the same as before the collision. Think of two billiard balls hitting one another, or two bowling balls.