No I've never heard of it before. But I've seen Jaimoe mention Jackie Avery several times in interviews.

The usual story is Phil Walden introduced Jaimoe to Duane and wanted Duane to put together a trio similar to Cream or Jimi Hendrix and Jaimoe had been in Otis Redding's road band and Otis was managed by Phil. Sadly Otis was killed in a small plane crash. 

Duane had his eye on the Second Coming bass player so the three of them went to Muscle Shoals to cut their first album. Jaimoe didn't want to play but live so Johnny Sandlin was brought in to play drums. They cut several tracks but Duane decided it wasn't happening and it was scrapped. Some of the tracks did get on the two Duane Allman anthology albums. 

Next apparently Duane and Jaimoe began playing with the Second Coming but Duane also was working on a new lineup for his band. Reese Wynans on keys, Duane, Berry and Jaimoe. Then Berry talked Duane into asking Dickey Betts to join because Berry liked working with Dickey and thought the twin lead Dickey and Duane was doing in Second Coming was real cool. 

Some days later they decided they needed a solid meat and potatoes rock drummer but keep Jaimoe because all those cool fills and accents he knew from those jazz records Jaimoe listened to were way cool so Butch Trucks was asked to join. I can't remember why they didn't ask the drummer for Second Coming. 

And finally Duane replaced Reese with Gregg because Gregg could sing better than the rest of them and he had several original songs they wanted to hear. I think Dreams was the first song Gregg showed the band but they rearranged it as they did all of Gregg's songs, something Gregg claimed  he never liked especially having such long guitar solos between the verses. 

One of the tracks from what was Duane's failed attempt at the first album for Phil Walden. 

I remember reading somewhere that Phil (I think) introduced Duane and Jaimoe because he didn't know if Jaimoe was any good. They jammed and saw a musical partnership. Supposedly Duane told Jaimoe that if he ever got a band together again, he wanted Jaimoe. Allegedly Jaimoe used to say he "was in the band when there wasn't no band."

Billastro

@billastro Yes I remember that too. Jaimoe was definitely the first to join. Then Oakley followed by Betts. Next was Butch Trucks and finally Gregg Allman. 

But Reese Wynans was there on keys and presumably if Gregg had decided to stay in LA Reese would have stayed. But what a different band it would have been. Don't Want You No More would sound the same except Reese instead of Gregg on organ but no It Ain't My Cross To Bare, Black Hearted Woman, Dreams, Whipping Post. 

And as was the case with the Second Coming when Duane, Butch, and Jaimoe would come out and join Dickey, Berry and Reese, Duane, Dickey and Oakley divided up the singing. 

Guess there is no getting around the fact the only way the band would make it to the big time in 1971 and sound complete was to have the six who who were in the band. 

This suppose to be Dickey singing with Berry and Dickey's then wife Dale Betts backing. 

This is Dickey to the right of the left handed bass player and it's the band Rick Derringer sings about in his hit single. 

https://images.app.goo.gl/aimU94Ldpsac4oRC9