So I know I don't have the "fast fingers" required to play an effective Duo Lon... However, I would like to contribute to the thread after being blown away by MadKOF's Duo Lon...
Here are some Duo stuff I've trying out to see maximum potential for his damage... Mainly HD combos... Also some corner specific combos...
4 meters HD - j.D, s.C, HD, s.C, f+A, (qcf+C, qcf+C, DC, f+A)x5, EX DM, Neomax = 873 dmg
Corner Specific - (Also possible mid-screen but does less damage and done a little differently)
1 meters - j.D, s.C, f+A, qcf+AC, qcf+C, qcb+A, s.C, (qcf+C)x3, qcf+B, s.C = 441 dmg
2 meters - j.D, s.C, f+A, qcf+AC, qcf+C, qcb+A, s.C, qcf+AC, qcf+C, qcb+A, s.C, (qcf+C)x3, qcf+B, s.C = 532 dmg
3 meters - j.D, s.C, f+A, qcf+AC, qcf+C, qcb+A, s.C, (qcf+C)x3, qcf+B, EX DM = 616 dmg
3 meters HD - j.D, s.C, f+A, qcf+AC, qcf+C, qcb+A, s.C, HD, s.C, f+A, (qcf+C, qcf+C, DC, f+A)x6, (qcf+C)x3, qcf+B, EX DM= 792 dmg
5 meters HD - j.D, s.C, f+A, qcf+AC, qcf+C, qcb+A, s.C, HD, s.C, f+A, (qcf+C, qcf+C, DC, f+A)x5, EX DM, Neomax = 976 dmg