Steel is steel but I bet projectile shape and mass has a bit to do with things. I'd expect the Dupleks to lose V fast, but maybe carry sufficiently to ??? (notice I asked for penetration tests in prev post at 50 yards, not 100).
In the old ads they showed guys shooting the slugs from overunders. My guess is that those were smoothbores, and maybe not even of rifle sighting. Within 50 yards maybe the steel has enough oomph. Dunno, we haven't tested them (hmmmm, sounds like a good range day coming up).
I live in a "used to be" slug only state.
Tuned 870s with WW HI Supremes were under 2" @100 yards. Trigger jobs, bought slugs from one lot #, and tested for fouling/cleaning intervals.
So I have a bit of knowledge in what it truly takes to get good repeatable groups from a slug gun. Also had a few Mossbergs. Usable, maybe even better in smoothbore than others.............but they aint all that great. My pumps good enough I see no need for a slower system (like a bolt slugger).
Flubbed a shot once, quick second saved the day (pump rig). I have smoked several deer on drives or on the run, with pump guns, but there the first and followups were on the money
I just shoot til their nose hits the dirt if I don't see obvious impact location.
Guys blew me crap over all the holes. I don't care. Deer rode to check-in in my vehicle, didn't feed the yotes or was taken by next door slobs.