I was asked a few times, if I want a broadcast-sheet that someone found in his Barracuda or Challenger. One with a different VIN Number, a few digits plus or less, from another car, (mistakenly) put in during assembly. Of course I should say yes. But I rather not, it would probably be in one of the drawers for ages.
This is my opinion:
If there is another broadcast-sheet in your car and the VIN does not match, please keep this paper ! It belongs to your car, your car came with it from the factory, this is
simply another rare thing on your car ! And this adds a small amount to the value, too.
If you give it away today, you will regret it tomorrow.
You can always post the VIN on one of the well known websites. If the car is out there, someone will contact you sooner or later and you can think about it what you do.