Duppy is patois for ghost, and producer Lee Perry and The Wailers conquered not just evil spirits, but much of the reggae world with this phenomenal number. But first Perry had to overcome his financial problems. He owed The Upsetters money, and understandably they had downed their tools until they had cash in hand.
So once again, the Soul Syndicate band were brought in in The Upsetters' stead, but Perry felt their rhythm didn't cut it (it did however, prove perfect for "Mr. Brown"), and making amends with the Upsetters, the backing was redone.
Play "Brown" and "Duppy Conqueror" side by side, and you can see the producer's point. The Syndicate's rhythm was forceful, but the Upsetters brought a razor sharpness to their sound that every conqueror needs. Overhead, Bob Marley strides forth, shaking off the chains that bind him, he is an uncontrollable force, nothing and no-one can stop him as he makes his way to Zion. Behind him, Peter Tosh and Bunny Livingston harmonies swoop and swirl around him, at times they twitter and coo like birds. Phenomenal!
Surprisingly, the band changed little about the arrangement when they recut it in 1973 for their Burning album, even the twittering harmonies remained the same.