On April 24, 2016 we received the following information from Booger Band keyboardist Will Boulware:

I only met Duane two times and the first time was when he came to my gig. I had a duo with a drummer (Joel Maloney). And Duane came to hear us and sit in. We played for about 15 minutes.
Then I saw him again at an after show party after one of his gigs, I think the Fox in Atlanta.

1971 sounds right. A mutual friend of mine brought Duane, Dickey Betts and Gregg Allman to our concert to hear us and sit in. It was a total surprise to me at the time. That is definitely the recording from that night. Joel Maloney the drummer used to have a copy.
And that was Dickey Betts in the background towards the end.

I can't remember the name of the place, I remember how it looked, and the location I think was somewhere off of the Bankhead Highway area. I played there twice.

(Thanks to Scott Cantor for contacting Will Boulware)