It's pretty hard to shoot someone elses bow and have it be on as far as the sights go. The demensions you use to set the pins and peep are different for every person. The Key is how well he grouped the bow, not where the group impacts.

He may have been torqueing the bow, and that is why he shot off from yours. But he also could have been lining up the sight differently as well. And the up and down was probably do to peep height and a difference in anchor point.

I have a freind that has a simular set up bow as mine as far as draw length and the such. If we switch bows the arrows impact in different spots, but still group well. His bow is about an inch too long for me though and has more draw weight. And the peep doesn't come close to lining up with my eye because we anchor differently and the demensions of your faces are different.

Paul