Joined: Sep 2015
Posts: 1,300
Likes: 210
From: Ottawa, Ontario, Canada
Bikes: TrueNorth CX bike, 88 Bianchi Strada (currently Sturmey'd), Yess World Cup race BMX, Pure Cruiser race BMX, RSD Mayor v3 Fatbike
Did you examine your ride next to his, do you know what equipment each of you use to track? Sounds more like an error of some kind than hacking files.
GPS has an error margin, and that can go up a lot from things like a low quality receiver, blocked or partially blocked antenna, etc. Also, who cares? You were both there and know what happened.