I also collected Pinkerton Cabinets since the mid 90's. I sold my last one in Goodwin's most recent auction (an SGC 70 Collins) . I have seen all kinds of Pinkertons but only count the actual photos or photos on mounts as described in the Standard Catalogue (which I believe to be the best source) as actual T5's. The postcards are an entirely different issue or issues . Information from REA or any auction house would be less credible than the Standard Catalogue in my opinion. Often when large groups of Pinkertons come to auction I have seen a variety of mounts. I suppose it is possible that people decided to mount the photos to non substantial paper like mounts. If the goal was to mount it to increase value, someone with that intent could find a cardboard mount and make it look closer to "real" then the paper or thinner and odd looking cardboard mounts that have popped up over the years. One thing that I look for is whether the photo is just glued at the very top of the image only which I understand is how they were distributed. If the entire photo is glued down SGC told me they would not give it a numerical grade just an A. This makes it hard to find them with numerical grades as it would seem likely that someone might add glue as the way it was mounted only at the very top is flimsy and could come loose. As far as PSA I think they graded it authentic based on their opinion of the photo being a true T5 photo which it appears to be. PSA has always been hesitant to grade Pinkertons and turned me down when I tried to submit some several years back
One thing is for sure it is a complicated set and hard to understand what is actually factory distributed and not altered or remounted. As a footnote which sheds further light on the value and desirability of Pinkertons, I walked around the 2018 National with the Collins T5 and several auction houses were interested. I showed it to several dealers including some board members. Most said it was worth 1,200.00 to 1,500.00. I thought 4,000.00 which is what Goodwin thought so I consigned to him. With the hammer it went for nearly 5k.
https://goodwinandco.com/LotDetail.a...entoryid=38184