I forebore [see what I did there?
] to mention Cape gun, since that was a very particular English type of thing, but yes, it has the characteristics of such a gun. A cape gun is a side-by-side version of a combination gun, and is typically European in origin. These were at one time popular in southern Africa where a wide variety of game could be encountered. British versions are commonly chambered for the .303 British service cartridge and a 12-gauge smoothbore barrel, with the rifled barrel positioned on the left. German and Austrian cape guns have the rifled barrel on the right side, which is fired by the front trigger. The front trigger is usually a set trigger as well. However, these are AHEM-style guns, and are not to be mentioned here - a muzzleloading Cape gun is way outside my area of knowledge - in all these sixty-eight years of shooting, I have never seen such an arm.*
A similar smooth/rifled mix could also be seen in the British 'Paradox' configuration, that had/has a smooth-bore 12 gauge and a rifled 12 gauge in SxS. The 12g smoothie was for shot, and the 12g rifled was for a ball - needless to say, both were/are c*r*r*d*e guns... H&H currently make rather a nice one, with a three-year waiting list, starting at $175,000 plus taxes, but after that it can get
really expensive.
*I ought to mention at this point, in case you get the idea that I'm older than Noah, that I started shooting at age six.