I worked during the last quarter of the 20th C for a gunmaker producing copies of a S. Hawken design rifle. We produced 176 of them over three years but they included a smaller version for small statured folks, a full stocked Hawken and a Hawken pistol. And though there were a couple of other workers in the shop from time to time, I had a hand in almost all of them. In my own shop. I have built about twenty Hawken rifles too; it was what the customer wanted.
I have built three A. Verner fancy rifles, each one better than the previous, but basically the same. Jaegers three, but all different. JP Beck's - several, but again, all different. Even with an original style, such as a Hawken, it is easy to personalize them and make each one a little different. And with well over a hundred muzzleloading guns out the door, it would be difficult not to make duplicates.