Sources:
1) Interview with Joe Dan Petty in 'Vintage Guitar Magazine', November 1996.

2) Randy Poe: 'Skydog - The Duane Allman Story' (Backbeat Books, 2006, page 285, paperback edition, 2008, page 291).
The cherry sunburst belonged to the guitar player of a band called 'The Stone Balloon'.

Update November 11, 2015:

This was posted on a Duane Allman fan page on Facebook:

"Well here's a new piece of information from Kim Payne - According to Randy Poe in "Skydog," Duane did secretly tell either Red Dog, Joe Dan Petty or Kim Payne to switch the pickups on the Goldtop and the cherry burst before making the trade, however, I just asked Kim and he recalls taking the guitars to a guitar shop in Decatur, GA for the switch to be made."

And also:

TRANSCRIPT OF "WITNESS STATEMENT"
(Dated 11/97)

1957 Les Paul Gold Top Standard
(Serial 7 3312)

"On the night of September 20th, 1970 [the correct date is September 16, 1970] the Allman Brothers Band played at the Peabody Auditorium in Daytona Beach, Fl. The opening act was a local group, The Stone Balloon. The band members consisted of Brad Yates, Rick Stine, Steve Hudson, Brian McMahon, and Dennis Culler.
Rick Stine and Brad Yates had jointly acquired a 1958-59 Cherry Sunburst Les Paul Standard. Duane Allman admired the guitar, and offered to trade his 1957 Gold Top Les Paul Standard (serial # 7 3312), a 50 watt Marshall amplifier, and $200.-. Rick Stine accepted the offer.
Rick Stine owned the guitar for a number of years, eventually selling it to Randy Roberts.
Randy Roberts sold it to another local musician, who in turn traded it in to Coastal Music Store owner Jim Omby. It was spotted by musician Billy Bowers, who, knowing the guitar's history, notified his friend Scot Lamar.
Scot Lamar, along with Peter Young, of Gainesville, purchased the guitar during the early summer of 1977. They currently still own the guitar.

This statement was compiled by myself, William M Bowers, and is true to the best of my knowledge, as witnessed by the others listed below:

(signed and dated)
Rick Stine
Jim Omby
Brad Yates
Bruce Parker
Randy Roberts
William M Bowers

(Thans to Michelle Wilson for this information)