There are many people on this board far more familiar with German proofs than I am. but I'll take a shot. It can be confusing because there are different systems for Imperial/Weimar/Nazi Germany before 1939, wartime/Nazi Germany 1939-1945, Communist East Germany ~1945-1992, West Germany 1945-1992, and reunited Germany 1992-present. Most of those systems saw subtle or obvious changes in marks over their respective timelines, and some specific marks are common to multiple systems.
My best guess for these marks
Germany, made between 1912 and 1939
Chambered for 12 gauge shells
Both bores between .719" and .729 diameter
Left bore choked
Proofed for smokeless (nitro) powder
No date code or chamber lengths marked. Would that narrow the dates?
If I've misstated anything, someone correct me, please!