I have run into a number of faked Walkers and Colt blackpowder pistols in general. If you attend enough gunshows and met enough "collectors", the number of aged Italian replicas pro porting to be originals is orders of magnitude greater than the original production quantity of Walkers. Maybe thousands of times greater the survival rate of actual original Walkers.
I think I read somewhere that someone complied a list of all known original Colt Walkers. I have not seen it, it would be interesting to examine.
Now somewhere, I have around the house, and so do you, a number of knives that you could sell to someone, claiming they were the original Bowie knife owned by Jim Bowie. I saw a television program where a guy went to a gunshow and bought, what he had been told, and what he claimed, was Jim Bowie's original Bowie. This guy then went home and cut the knife up into four or five pieces with a chop saw. He still believed it was original and wanted to show's historians to prove originality. What they proved was that was left of the grips was mammoth bone, and thus, unlikely to be Jim Bowie's knife.