Duncan was created in Part 19 of the first season to attend Luna's teen party. Duncan was known as the Snob of the original "New Kids on the Block": a group that consisted of himself, Dedrick Hudson, Tori Dunbar, Janice West and Braden Ramey.
In Part 35: Prom Duo, Duncan is spotted hanging out with the rest of the New Kids at The Sandy Place: the group's secret hideout. LifeSimmer stated that when Duncan was a Teen, he had really cool hair, which he lost upon aging into a Young Adult.
He did not appear in second season.