You've both got the same draw length, correct? Draw length makes a big difference with arrow speed. I'd also measure both bows on the same scale to make sure they really are pulling the same weight.

Assuming your bows are identical in every way (draw weight, draw length, arrow rest, peep and string silencers), I'd suggestyou both go to the same chrono with your identical bows, and shoot the same arrow through the chrono. If you get dramatically different speeds, then you must have a tuning issue with your bow. Check cam timing, axle to axle length, brace height, and all that stuff.

If both bows are tuned the exactly the same, yet his bow shoots a little faster, maybe he's shooting hard off the back wall and you are creeping forward before the shot.