The pictured pistols appear to be one flintlock and one percussion-cap. It is my understanding that (a) duelling pistols were supposed to be identical, thus affording no advantage, and (b) that the percussion cap was invented later than 1804. Unless one of the pistols was subsequently modified (why?)...
Can anyone shine a light on this one?
Not only that, the fore-grips, pistol grips and trigger guards are different. Possibly the photo is fake-but-accurate?