Bruce Anstey made up the disappointment of Monday's disqualification from the Supersport Junior race one by taking this morning's race two.
In addition the New Zealander set a new lap record for the race on his second circuit, clocking 125.395mph
Ian Hutchinson was second, with Ryan Farquhar making up the top three.
The Irishman also picked up a trophy for having the quickest aggregate time for the two Supersport races.
Manx Radio TT's Charlie Lambert described the Flying Kiwi's victory:
Ben Birchall: Sidecar TT competition 'good for the sport'
14-time winner says new teammate Rousseau 'ticks all the boxes'
Snooker: Cue Zone Blinders retain league title
Three-way tie for individual league crown after season finale
Football: Peel win Women's FA Cup to secure season double
Corkish double helps westerners beat resilient Onchan
London Marathon: "some great performances from Isle of Man runners"
Results from Sunday's event
Cycling: Cavendish to return to racing this weekend
38-year-old has had a spell out due to recent illness
Ravens conjure stellar comeback to beat AFC Liverpool
FC Isle of Man recover from two-goal deficit to win
