Definitely a very neat and odd looking 38 SA. There are four 10" guns listed in the SWCA database and two of them were in a 2 barrel set. Am I seeing a serial number in the 65XXX range? If so, shipping would have been in the early 1880s. Does the serial number on the cylinder and butt frame match? There are also serial numbers on the rear of the top strap between the "ears" and another on the bottom of the top latch. Lastly, the right stock should have the same serial number.
This barrel length is quite rare, but you have to put it all in perspective. If there was a lower condition level than poor, that revolver would be in it. If a 10" barrel is worth 2X or 3X more than a standard barrel length, how much is it really worth? A standard barrel length revolver in that condition would be worth less than $200.