There is always human error when it comes to data entry. Now with that being said I have seen pop's that were a little off or letters or numbers left off by accident. I have also seen hidden vins that are a number off from the actual vin plate in the dash. Anymore almost nothing is 100%.
After rereading your statement/question I see what you are asking now. Yes there are many different fake pop's out in the world. That should not be the only doc that a person should verify. As twisted as this world is if you want to be 100% correct with a purchase of a car you have to do your homework. IF you are still uncertain; there are people out there that will look a car over for you for $$$..