Caproni Ca. 161bis

I'm out wandering around on the internet and I stumble across a page of aviation trivia and one of the items listed is the "highest flying propeller driven airplane", and I wonder what it is, imagining some WWII experimental job, or a Burt Rutan outer space special. So imagine my surprise when I find this:

An Italian biplane flown by one Mario Pezzi in 1938, encased in his own personal pressure chamber:

The 750 HP radial engine has two superchargers. I wonder whether they were operating in tandem or in parallel. I mean there isn't much air up at 56,000 feet. The blades on the prop look they were made for a paddle boat.