Yeah, the stacking of 112's is absolutely "a thing". I have two of the Eden EX-112 cabs which are their low-end series. Bought one for a small venue we play all the time and it sounded so good that I got a second one. I'd stack those for medium venues and they sounded really good. No question that acoustic coupling adds a lot on the bottom end.
And of course, Eden stopped making the single 12's in their EX series so once they are sold out they are gone. The D112XST's should still be available. If you're going to buy their top of the line though, I'd suggest you take a look at the DNA-112's (I am on their Endorsing Artists Roster).
David designed all those D-series Eden speakers when he owned Eden and his DNA-112's are better yet. They have a very flat frequency response, higher power handling, and will even sound good with a stand-up using a bow on the strings. I'd suggest putting in a little bit of low-mid boost to to them because it gives great definition and presence when playing in a group. Besides the fact that they are just better cabs than his D-series were (clearer, and more articulate, higher power handling), since Eden moved their cabinet manufacturing to the UK at their Marshall cab facility, their prices went up considerably and DNA cabs are less expensive than them now. Hard to beat better sounding and less expensive too.
Back to those inexpensive EX112's real quick though. They are very compact because they use a whizzer cone (cone within a cone) instead of a separate tweeter horn. I would not have considered it if a friend, Paul from the UK, had not recommended it continuously for about 4 years before I bought one. They don't sound as good as the D112XST cabs do but there's no where near $600 difference in the sound that there is in the D-series price tag. My EX112's were $269 each (handles 300-watts rms) and I continually got compliments on them when I used them.
Here's a shot of the set-up I used for medium-sized venues with two of them stacked on their sides, aligning their shelf ports. I bought the first one in 4 ohm so I did the same with the second one. Should have bought them in 8 ohm. They are so compact that even turning them sideways, my Eden WT500/800 amp hung over the sides.
View attachment 4072088
Compare that to the next pic which is my small venue rig using just one EX-112 standing upright and a small and light Eden TN226 amp on top.
View attachment 4072089