Watch the Duane Allman online guitar lesson by Jeff McErlain from Kings of Tone
Duane as far as I can tell didn't really use pedals, so what I try to do is find a pedal that most closely sounds like my favorite amp when it is cranked. I don't get any kickbacks but for the Duane tone ( and most things classic Marshall) I love my Z-Vex Box of Rock, largely because it sounds a lot like a cranked Marshall Plexi, my favorite amp. It's good to remember that not all OD boxes sound good with all amps. So it helps to have a few if possible, there are a lot of really great pedals out there at every price point.