The Hill City-University athlete threw 29.86m on her second attempt in the javelin at the Caledonian Ground on Saturday.
It broke the previous women’s 14-aged record of 28.74m, the distance Duff also threw on her fifth throw.
She also threw 35.16m to win the open women’s discus to complete an impressive start to the season.
Taieri’s Dyani Shepherd-Oates also had an impressive day in the hammer, her 55.52m throw an exceptional early-season effort.
Kieran Fowler’s 46.05m in the discus was the most impressive men’s throwing performance, while Jamin Millar (HCU) managed 43.08m in the javelin.
On the track North Otago’s Schuyler Orr ran 11.91sec to win the men’s 100m in a tight race with Taieri’s Millar McElrea and Caversham’s Hadlee Edmunds.
Nelson’s Celia Ward delivered a 12.93sec performance to win the women’s race.
In the 400m Richmond’s Samantha Hardie had a comfortable win in the women’s race, clocking 61.10sec.
Liam Prouting-Gardner (North Otago) won a tighter men’s race in 52.18sec.
Zara Geddes (HCU) and Catherine Lund (Ariki) battled to a stalemate in the women’s 1500m, finishing tied for first in 4min 48.60sec.
Josh Hou (HCU) won the men’s race in 4min 19.49sec.
