Steve, just general thoughts. The bluing may have been done at a later date and at a time when damascus wasn't appreciated as much. I'd guess that even if one or the other gun used tubes that were made as a backup, the serial numbers may not turn out to have much relation to each other.
The blued gun, or both, could be interesting. It's possible that neither is a showcase gun, but probably cost some price premium. The gunmaker may have wanted a set or more of special tubes, but I wonder if a barrel maker wanted to advertise their skills. There was probably some point in time when gunmakers didn't know that was possible, and the skilled barrel maker may have wanted to demonstrate it to the trade. Only thoughts, I'd really like to see your document, great stuff.
