[mega_dean]

> If our understanding of physics is right, it doesn’t matter whether you hit them or they hit you.

That was my first thought too, but I don't know if it's true because of the strings they are attached to. The striking conker is at the end of a taut string the entire time, but the receiving conker is hanging loosely and bounces around after being struck. My guess is that the taut string helps with energy dissipation after a collision, but I could be wrong. And either way, it might be a negligible difference.