Assume a proton or neutron is flying around a collider counter-clockwise at 99.99% of the speed of light and collides head-on with another proton or neutron going clockwise at 99.99% the speed of speed of light. (The exact particle and exact percentages are irrelevant to the question.)

Is the effect of that collision the same as if one of them were travelling more than the speed of light and collides with a stationary particle?

Or is the energy needed to go from 99.99% to 100% greater than the energy needed to go from 0% to 99.99%?

Thanks.