Duacell or Duracell? If you mean the Duracell batteries sold by Sam's Club, those are made by East Penn Manufacturing. I have a quartet of Group 31 AGMs on Voyageur, but they're not yet a year old so I can't comment on longevity etc.
They aren't really "Duracell" batteries. East Penn and many other prime battery makers slap all sorts of OEM labels on batteries. They do have a great reputation for being a great battery at a great price.