The former Scotland U20 skipper was part of Glasgow's academy contingent over the last two seasons.
Duncan followed in his fathers' footsteps and started his rugby career playing for his local rugby team, Loch Lomond, at the age of five years old.
He has attended several clubs throughout the years, such as West of Scotland FC, Cartha Queens Park RFC and Boroughmuir Bears.
Munn also gained a rugby scholarship to Kelvinside Academy in 2019.