I have seen this in pretty much any type of mechanical/motorsport competition I have been involved into one degree or another. It was always very common at drag races. Most any racer would let others borrow tools, parts, etc., even if it didn't help the lender.
Most competitors, myself included, preferred a race to a competition bye, and wanted to see everyone do the best they could. Occasionally, someone would be helped by a racer they would meet later, and borrower would beat the lender with the borrowed part. At the end, the winner would pull the part off the car and return it, or pay for it, no animosity between them other than good ribbing.
It has happened to me from both sides. I have raced with a borrowed supercharger, torque converter, rear end gears, etc., and lent tires, wheels, ballast weight, lots of electronic parts. I generally tried to help others as much as I might expect it from them.