"Dupe" is a strong word. Very few people take the time to investigate banjo history and much of the "generally known" info has turned out to be false.
There also exists the possibility that there is no discernable difference between the first series and the later examples. I, personally would not know the difference.
With classic era banjos, always expect the seller to be ignorant and you will need to know more. You are young, you will make mistakes and be sold bad or misrepresented banjos. That is, sadly, tuition of life. I have found that even "reputable dealers" with long experience dealing banjos can be just as ignorant as random ebay sellers.