Real precedents for Smolensk's stacked gun mount

Was Smolensk's stacked four-gun turret arrangement ever tried in real life?

The exchange recalls smaller mounts and an Italian 15-inch paper proposal, but does not identify a built and tested heavy-gun example.

The game mount puts two pairs of 130 mm guns one above the other. No built example larger than about 40 mm is recalled in the exchange. Italian designers did consider a comparable arrangement for 15-inch guns, but that paper proposal is distinguished from a built and tested turret. Italy's sale of designs to the Soviet Union is offered as context for the resemblance, without establishing that the game mounting entered service.