Brian Eather made the only four blades I'm aware of. He made me a some props about 2 years ago. He comes in and out of retirement occasionally to make a few. Don't know his current situation.
NO not really
Bolly made many 4 blades before that, I sold many to CL stunt guys in 10 10.5 , 11, and 12 , 12.5 inch 4 blades
Ronnie Farmer, Bob Gieske , Jim Casales , I used some of them as well as dozens of others going back to the 1980s, may wanna look at Dougie too :-)
I even have 4 blade spinners
randy