Hi Mel,
The Anzani six was indeed an interesting engine and as you say, the first double-row radial and identified by its two separate exhausts collectors.
The Wiki listings for applications using this engine is far from complete and they were quite widely used, but this one isn't Polish!
Yes, this was from the 1920's and as you correctly surmised, it wad a single engine high-wing cantilever monoplane.
Good hunting
