A cape gun is a combination gun with one smooth and one rifle barrel side by side.  IIRC, they're named after the Cape of Africa, where they're popular for simplifying carry--one gun, two purposes. They're also found in Europe more than the US.
This example is German, from about 1800.  It was some family's beloved hunting arm for close to a century, judging from the wear.
Probably in the 1970s, some jackass JB Welded a veneer over the cheek rest, but didn't prevent worm infestation.  I removed it.
Which matches with a much larger repair and repair to the repair previously done on the left side.
 
You can see silver pins where the cheek piece was a later add on, and a repair to the heel of the stock.
