This is a pair only in that they were assembled sometime after the first was produced, by an individual who for some reason didn't order a pair of guns to begin with.
I can relate to that kind of constraint.
I have a composed pair of Mossberg 500s, in twelve gauge. They were produced about 30 pheasant seasons apart, and one is the dreaded "New Haven" version, and has been painted black, but, by golly, they ARE a composed pair. I expect the premium I'll be paid for selling this composed pair will compare favorably to the premium you will receive for the Horsleys. But, if the Horsley's had been built together, serial number sequentially, and cased together with tools and what-not, you would do better.
They weren't. Bummer.
Might be a good time to start looking for that generals decendants, and, hoping they have more money than common sense.
Good Luck.
Best,
Ted
