Meanwhile, Olympic and world champion Duplantis suffered his first Diamond League defeat in three years.
In March, the 26-year-old broke the world record for the 15th time, with a jump of 6.31m slightly north of Stockholm in Uppsala.
But the best he could muster on Sunday was 5.80m, second to Australia’s Kurtis Marschall (5.90m).
There was one local win in the men’s discus for Daniel Stahl, with the world champion’s throw of 69.60m beating Australia’s Matthew Denny (69.02) and Slovenia’s Kristjan Ceh (67.67).
Britain’s Lawrence Okoye was eighth with 64.02, some way short of his season’s best (71.88).
In the women’s 100m, Britain’s Amy Hunt ran a personal best 10.97 seconds to finish second to America’s Melissa Jefferson-Wooden. Dina Asher-Smith was sixth in 11.24.
British sprinter Jeremiah Azu was disqualified after a false start in the men’s 200m, which was won by American Kenneth Bednarek in 19.87 seconds, with South Africa’s Sinesipho Dambile second in 20.10.
GB’s Elise Thorner was second in the women’s 3000m steeplechase, finishing almost 12 seconds behind Tunisia’s Marwa Bouzayani, who won in a meeting record eight minutes and 59.28 seconds.
Charlie Dobson was fifth in the men’s 400m, won by South Africa’s Zakithi Nene in 44.48 seconds.
The men’s 800m was won by America’s Cooper Lutkenhaus in a season’s best one minute 42.70 seconds, with GB’s Ben Pattison (1:43.70) and Jake Wightman (1:44.39) fourth and seventh respectively.
American middle-distance runner Yared Nuguse outlasted 19-year-old Australian Cam Myers to snatch victory in the men’s 1500m.
There was another meeting record in the women’s shot put with the Netherlands’ Jessica Schilder registering 20.89m.