Word was that certain cartridges had a screen that would tell you that you won whatever prize was part of the contest associated with Vectorman, and that screen showed up only after beating the game. That got me thinking, does that mean that cartridge has a distinct ROM? Or did all cartridges use the same ROM and maybe there was some other programming nonsense in the ROM that would trigger the contest win screen? I don't recall ever hearing about or seeing a distinct ROM dump of a winning cartridge.
I was thinking about this before falling asleep last night, and my initial theory was that all copies of the game might have the "You Win!" screen in them set by a flag before burning the game to ROM. The back of the box describing the contest implies that the winning carts would be chosen at random, which bolsters this theory. But upon waking up, I realized that if they custom manufactured the winning carts so there would only be X copies in existence, they could have made a separate revision just for that.
Custom manufacturing 10 101 competition carts seems excessive to me given how easy it is to flip a flag, but we're also dealing with a contest where costs like that would be set aside. It's also possible that the "You Win!" screen is triggered at random upon starting the game, so the "only winning copies" thing might refer to how many players first won the competition. It's been ages since I've beaten Vectorman without cheating, so I can't remember if I ever encountered the special "You Win!" screen.
If the competition screen is baked into every game, there should either be a Game Genie code to unlock it, or a romhacker should have found dummied out code for it in the base ROM. I have no clue if anyone has done a deep dive into Vectorman's code, so maybe nobody has bothered to look for the contest code?
Edit:
Apparently there were up to 101 winning carts, I was just misreading the contest details. There was at least one grand prize winner, but I wonder if there were ever any runner ups?