Duplantis celebrated in his usual exuberant style as he set a new mark of 6.26 metres in the pole vault, less than three weeks after he last broke it when defending his Olympic title in Paris.
The 24-year-old Swede was congratulated by Polish President Andrzej Duda, who came onto the track and shook his hand.
"Everything just came together to allow me to do this," said Duplantis, whose first world record also came in Poland in February, 2020.
"I know a lot of people came here to see me jump, so I wanted to put in a good showing for them.
"This year I focused on the Olympics, the record just came naturally because I was in good shape.
"So I am not surprised with the record today, but I am thankful."
In the 3,000 metres, Ingebrigtsen, who lost his 1500m Olympic crown but won the 5,000m title, held his hands to his face in astonishment, then on top of his, head mouth agape, after posting a time of 7min 17.55sec.
The 23-year-old Norwegian smashed Kenyan Daniel Komen's 28-year-old mark by more than three seconds.
"It feels special, amazing," said Ingebrigtsen.
"I was hoping to challenge the world record here, but based on my training, I can never predict exactly what kind of time I am capable of.
"I would not have imagined I could run 7:17, though."
Kenya's Olympic champion Emmanuel Wanyonyi had entertained hopes of breaking compatriot David Rudisha's 800m world record of 1:40.91 set as he won Olympic gold in London in 2012.
However, Wanyonyi's thunder was stolen by his great rival over the distance Canada's world champion Marco Arop, who looked on course to set the record himself until tying up in the final few metres.
Arop, who took silver behind Wanyonyi in Paris earlier this month, finished in 1:41.86.
Expectations had been high for Wanyonyi after he went within 0.20sec of Rudisha's mark in Lausanne last Thursday.
Nevertheless he sounded less than enamoured at the hype that had surrounded him potentially breaking the record.
"My body did not respond well but I have done my best," he said.
"I do not like when people say that I am going to break the world record.
"I do not want to say anything about the record." 'Fire in me'
Another Olympic champion from Africa, Letsile Tebogo, made no mistake in the 200m. The 21-year-old Botswanan swept imperiously past American Kenny Bednarek, who had led into the straight, to win.
Tebogo, who was awarded two houses and a diamond on his return home following the Olympics, timed a meet record of 19.83sec.
Femke Bol and Karsten Warholm both set meet records in the women's and men's 400m hurdles, showing they had shrugged off the disappointment of failing to win the Olympic titles in Paris.
Dutch star Bol had cried after she failed to mount a challenge to Sydney McLaughlin-Levrone in Paris, finishing third, but with the American absent won her second Diamond League race inside a week, timing 52.13sec.
Warholm has had to get over his Olympic disappointment in being dethroned as champion by Rai Benjamin, the Norwegian doing it in the best way possible in a time of 46.95sec.
"I wanted to do this race well before the Diamond League final (Brussels September 13/14) so it feels nice to come out and to see the momentum going after the Olympics," said Warholm.
"It has been tough getting up after such a big competition, but today felt good."
The charismatic 28-year-old said he hoped he would never again run as flat as he did in the Olympic final where he still took silver.
"I did not have it in me in the most important day of the year," he said.
"We need to go back to work and to make sure it does not happen again.
"As long as I have the fire in me, which is still burning right now, I will keep on going."
