The Edinburgh University archer fought back from 2-sets down in the final, to take the match 4-2, completing a fabulous weekend.
Duncan was up against the formidable American Reo Wilde in the men's compound final - with Wilde scoring a perfect 18 10s during the match.
The British archer was also in fantastic form, and three of the five sets were decided on a one-arrow shoot-off, including what proved to be the decisive fifth set.
Trailing 3-1, Duncan needed to better his opponent in a shoot-off for a second successive set. Both shot 10s yet again, but this time it was the American's arrow that was fractionally closer to the centre, giving him the set, the match and the gold medal.
Archery GB is sponsored by Foresters Friendly Society
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