Duke H.
"DER neue Stockel" indexes three Duke:
R.& W Duke Birmingham, 1854
Robert Duke Birmingham, 1834-39
W Duke Birmingham, 1822-25
This type of double pistol assembled brass at often an English origin.
Unfortunately, no other information makes it possible to confirm this origin.
Greetings
Chris
Letters on the left turntable sound awkwardly printed. I believe that the weapon was punched by one of its owners or to add more romanticism (H. Duke can be read like haidouk (outlaw)), by a tradesman of weapons. Personal opinion, not checked!!
CristianR