Duncan played four seasons with the University of North Dakota Fighting Sioux where in 2007, he won the Hobey Baker Award and was named the WCHA Player of the Year.

Undrafted, Duncan signed an Amateur Tryout Contract (ATO) with the New York Islanders on April 8, 2009, and played two games for their American Hockey League affiliate, the Bridgeport Sound Tigers.

[2] In two seasons with Salzburg, Duncan mirrored each year in claiming the Austrian Championship and finishing as the Red Bulls second leading scorer.

[4] On July 4, 2013, Duncan signed a contract in a neighbouring league in Germany, on a one-year deal with EHC Red Bull München of the Deutsche Eishockey Liga.

On June 17, 2014, Duncan opted to remain within the Red Bull sponsored teams, in returning to Salzburg for a third time, on a one-year contract.