You shouldn't be getting downvoted - you're right. Doubling your speed against a brick wall quadruples the energy involved in the collision, but two equivalent

You shouldn't be getting downvoted - you're right. Doubling your speed against a brick wall quadruples the energy involved in the collision, but two equivalent objects colliding at the original speed only doubles it. If they have the same or similar mass, the energy is absorbed equally by both, and so if two equal-sized people run into each other at 10 kph, each one of them will feel an impact equivalent to running into a brick wall at 10 kph, not 20 kph.