Duncan represented Canada at the 1964 Winter Olympics in Innsbruck, Austria competing in all off the men's alpine skiing events. In the downhill competition, he placed 34th with a time of 2:30.06 (+11.90). He finished in 19th place in the men's slalom with a total time of 2:19.10 (+7.97). In the men's giant slalom, he finished in 26th place with a time of 1:58.44 (+11.73).