For what it's worth, "Hudie" is a common Irish nickname for Hugh (Aodh in Irish). It's not surprising that it showed up in the American South. He may have called himself "Hudie" early in life, no matter how it was spelled, and then later, because of the spelling and hearing people who'd never heard the name pronounce it as "Huddie," given in and started pronouncing it that way himself. That would account for a recording of him pronouncing it "Huddie" and other people's recollection -- and Alan Lomax -- of him pronouncing it "Hudie." (Names were often written down wrong in official records, especially when the parents or subjects are illiterate themselves.)