Parallax can cause different points of impact at distances other than the distance at where the parallax is adjusted for,however the amount of difference is far more than parallax can explain.I have seen this situation before and there are acouple of likelypossibilities.Are you both resting the stock on the rest?Is one of you resting the barrel on the rest?Resting the barrel is poor practise as it can cause a very different point of impact.The other likelypossibility is that one of you has terrible shooting form and is pulling the gun off target as you pull the trigger.To determine which of you it is ,have a few other people fire the gun and most likely their points of impact will be very close to one of yours but not the other.I helped a fellow that was scared of recoil sight in his rifle and after sighting it in perfectly he fired the gun only to find ithigh and to the side byseveral inches.Another shooter fired the gun andhis point of impact was the same as mine.He still wouldn't believe me so yet another person fired the gun with the same results as myself and the other shooter.Only then would he believe me about his flinch.