Having already won the pole vault, Duplantis cleared 6.05m with his third attempt to break his own stadium record in the last series event before next week's Zurich Diamond League Final.
After a lengthy delay caused by a measuring defect, the Swede attempted what would have been a new world record of 6.19m.
But even with the whole of the crowd inside the King Baudoin Stadium cheering him on, Duplantis had three failures meaning the history books will have to rewritten another day.
Meanwhile, Namibia's Christine Mboma kept up her excellent recent form with victory in the 200m.
The Tokyo silver medallist produced her trademark fast finish to win in 21.84, the same time as she recorded in the U20 World Championship in Nairobi two weeks ago and just three-hundredths outside her world junior record set in the Tokyo final.
American hopeful Sha’Carri Richardson needed a win to make next week's Diamond League Final, but could only finish fourth in 22.45.
Mboma's conqueror in Tokyo, Elaine Thompson-Herah, withdrew earlier in the week with discomfort in a tendon but is expected to be fit for Zurich.
Dutch star Sifan Hassan was a wide-margin winner in the women's mile but could not trouble her own world record of 4:12.33 set in Monaco in July 2019.
Despite having two pacemakers and Wavelight technology to assist her, the double Olympic champion from Tokyo was more than two seconds outside with a time of 4:14.71 although that was a meeting record and the fastest time in the world this year.
Axumawit Embaye of Ethiopia was next, more than six seconds adrift, just ahead of Australia's 1500m Olympic finalist Linden Hall.
Hassan said afterwards, "I'm really happy with the time. After Tokyo I was so tired so I just wanted to run the short distance. My goal was to run fast here tonight and that is what I did.
"I was not thinking about the world record although I knew I was on world record pace in the beginning. But in the middle, it slowed down a bit. It does not matter.
"I am not running any long distances anymore this year. In Zurich I will run the 1500m."
That almost certainly means a mouthwatering rematch with Kenya's reigning two-time Olympic champion Faith Kipyegon.
Francine Niyonsaba continued her successful reinvention as a long-distance runner with a new Burundian national record of 14:25.34, almost 30 seconds inside her previous personal best, to win the 5000m.
The Rio 2016 800m silver medallist switched to longer distances after being found to have elevated testosterone levels, and she produced a devastating sprint finish to win from Ethiopia's Ejgayehu Taye and Kenya's two-time Olympic silver medallist Hellen Obiri.
Niyonsaba said, "It was fantastic to run here. I enjoyed every second of it and the national record is the cherry on top. To be able to run for a crowd was funny. It really helped me.
"I still do not know if I like long distances more than the 800m, but I love challenges. I won't think too much about it because it is what it is. I'm still learning and am sure that I can go a lot faster in the future."
Michael Cherry was an impressive winner of the 400m after just missing out on the individual podium in Tokyo.
The relay gold medallist clocked a new personal best of 44.03 to break fellow American Michael Johnson's meeting record by three-hundredths of a second.
Ukraine's Yaroslava Mahuchikh won an exciting high jump with three women clearing two metres.
The three medalists from Tokyo all ended up on the podium again but in a different order with Mahuchikh's first-time clearance at 2.02m proving decisive.
Home favourite Nafi Thiam, fresh from successfully defending her heptathlon title in Tokyo, was sixth after equalling her season's best of 1.92m.
Olympic silver medallist Fred Kerley came through late to take his first win in the 100m since May's Ostrava Golden Spike.
Bromell was second in 9.97 with Norman clocking a season's best of 9.98 in third.
Kerley told the media, "I'm happy with the win, but I'm not satisfied with my race. I didn't execute the race how I wanted. That gives me working points because I always want to be better."
Speaking about his second place in Tokyo behind Italian outsider Marcell Jacobs, he said, "People say that his win was a surprise, but everybody works so hard to be the best and to be ready for the championships so there are no surprises.
"I'm very happy with the silver medal I won because it makes me one of the fastest sprinters in the world."
Nadine Visser got the better of two women who finished in front of her in Tokyo to take the 100m hurdles.
Steffin McCarter saved his best for the Final 3 as he took victory in the long jump.