I have a recording where Sonny taes the first two breaks, then Brownie says, "I'm gonna play some blues . . .if you'll let me."
Their awkward friendship was no secret.

I became a Josh fan first because I didn't even hear Brownie and Sonny and Big Bill till 1961 or 1962. I saw Mississippi John and Rev Gary Davis and Skip James in the summer of '64 and became a huge fan as well.