Duell's credits include the original Broadway production of 1776, as well as the film version of the musical and its 1997 revival. Among his other theater credits are The Ballad of the Sad Café, Illya Darling, Stages, The Inspector General, and the 1996 revival of A Funny Thing Happened on the Way to the Forum. His last Broadway appearance came in 2000 when he performed in Roundabout Theater Company's revival of The Man Who Came to Dinner.
His other film credits include One Flew Over the Cuckoo's Nest, Police Squad, Cradle Will Rock, The Out-of-Towners, Ironweed, Mrs. Soffel, and King of the Gypsies, among others.
He is survived by his wife, actress Mary Barto.