there are some debates about what songs had been played by Duane Allman,here follows the main informations I found around the web:

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on hittin the web
http://www.allmanbrothersband.com/modules.php?op=modload&name=XForum&file=viewthread&tid=51559

Randy Poe (http://www.skydogbook.com/) says so:
Duane definitely played on "Hey Jude," "Toe Hold," "My Own Style Of Loving," and "Born To Be Wild."
Ingemar Pijnenburg says he thinks Duane also played guitar on "Save Me." And Stuart Winkles' DA discography in Goldmine says Duane played on "A Man And A Half." I couldn't say for sure whether Ingemar's right or wrong about "Save Me," but that ain't Duane on "A Man And A Half." That's Bobby Womack, without question.

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on Allman Brother Band Discography
http://www.abbdiscography.com/cdheyjude.htm

According to Stuart Winkles' article 'Duane Allman - Skydog's Sessions '68 - '71'
(published in 'Goldmine' magazine, vol. 12 no. 8, issue 149, April 11, 1986) Duane plays on tracks 2, 4, 6, 7 & 10.

In the liner notes of the CD "A Man And A Half - The Best Of Wilson Pickett" is mentioned that the song "A Man And A Half" was recorded on September 19, 1968 and the guitars were played by Bobby Womack and Jimmy Johnson.

According to Ingemar Pijnenburg, a Duane Allman researcher
from The Netherlands, Duane plays on tracks 1 (overdub on right channel ), 2, 4, 6 & 10.