Duncan also played for Kentucky State University in the Division II SIAC conference during the 1997 season when he helped the Thoroughbreds win the inaugural Pioneer Bowl.

Duncan was the starting placekicker for Oklahoma's 2000 BCS National Championship team.

Duncan played two seasons for the Arizona Cardinals backing up starter Bill Gramatica.

Due to Gramatica's inconsistency and injury problems, this made it a necessity for the team to keep two kickers.

On March 30, 2004, Duncan signed a two-year contract with the Philadelphia Eagles, only to be released August 30.