Your assumption is usually correct. Only the wealthy could afford to shoot where pairs were required and they did not generally buy poor quality guns. However exceptions must exist!
A work of caution, it costs little to engrave a number '1' or '2' on a gun, gold inlay is not that much more, so this might be a clever way of raising the perceived quality (and price) of an ordinary gun.
Unless of course you have seen its mate and can confirm that they are effectively identical.