I agree there are almost certainly some forgeries and it might be impossible to tell them apart.
When I was querying it, I sent in 4 different examples and was told he used all 4 of those signatures on various memorabilia.
The reason I queried it at all was that I bought 10 sets from someone a couple years ago and got the 4 different autographs in those 10.
I later found out that Josh had supplied most of those 10 sets but over a number of years and from various sources.