Your question is what the "world" marketplace considers a matched pair. That's a pretty ambiguous question. Most of the world may presume you are referring to things other than shotguns. Better, IMO, to ask what is the definition of a matched pair of shotguns. It is a question that is based on English tradition, because we Americans are/were not concerned with matched pairs of shotguns unless we are/were Anglophiles.
My understanding of it (and my understanding is a minuscule component of the "world" view, no?) is that it is a pair of guns that are as near identical as is humanly possible. Even to the grain structure and flow in the wood, the weight, the balance, the finish .............. everything.
Hallowell's defines it as "Two shotguns of a matched Pair are identical in every way---same barrel lengths, same chokes, stocks of the same dimensions cut from the same piece of wood, identical weights, balance, etc. They should be consecutively numbered and all the readily-detachable components should be numbered 1 and 2 respectively. Usually, they are cased together. Ideally, in the heat of a driven shoot when the birds are coming hard and fast, working with a loader, the shooter shouldn’t be conscious at all of which gun of the pair he has in hand at any given moment. A "pair' of guns ordered with different chokes or other differences, in the interest of increasing their range of utility, defeats the entire concept of a matched Pair. Most makers will charge an extra 10% over the cost of two single guns for their trouble insuring the precise matching of the two guns. A Composed Pair of guns is one where two separate guns, made individually, are subsequently stocked or altered to match as closely as possible."
If I ever desired a matched pair, which I supremely doubt I will, I would consider 10% a small price to pay to have two "identical" handmade guns.
