Canadian Mikael Kingsbury added silver in the men's final. He crossed the finish line 2-100ths ahead of teammate Bilodeau, but the judges deemed Bilodeau superior over his two jumps for an 18-17 win.
The result gives Bilodeau his third consecutive dual moguls world title.
It was a reversal of the finish in individual moguls earlier this week, when Kingsbury of Deux-Montagnes, Que., was first and Rosemere, Que., native Bilodeau placed second.
"I'm happy it fell on my side today," said Bilodeau, the 2010 Olympic gold medallist in moguls. "We're finishing the week on a good note."
Dufour-Lapointe overcame a slip at the top of the hill to take gold in the women's event, just ahead of Miki Ito of Japan, also by an 18-17 score.
"I'm so happy, I don't even realize it right now," the Montreal native said.
Dufour-Lapointe said after the win she was happy to land on the podium just like her younger sister did earlier this week. Justine Dufour-Lapointe won bronze in individual moguls, but fell 19-16 to Chloe in preliminary round action on Friday.
Kingsbury, the leader in the World Cup points standings this season, was satisfied with his performance.
"The final was super tight, it could have went either way like everyone's saying, but I'm happy my teammate takes it," said Kingsbury. "We're just going to have a good time after the event."
Quebec City's Phil Marquis was seventh and Marc-Antoine Gagnon from Terrebonne, Que., finished 15th, both falling to Kingsbury in head-to-head matchups.
Americans finished third Friday in the dual moguls finals, with Patrick Deneen and 2010 Olympic gold winner Hannah Kearney landing on the podium.
Andi Naude of Penticton finished seventh, losing to Kearney in the quarter-finals. Audrey Robichaud of Quebec City was ninth, and Justine Dufour-Lapointe finished 15th. So far, Canada has raked in seven medals in these World Championships, which continue tomorrow with slopestyle where JF Houle of Drummondville, Que., Kaya Turski of Montreal, Dara Howell of Huntsville, Ont. and Yuki Tsubota of Pemberton, B.C. will make their runs for the podium.
All told, Canada has won seven medals at the world championships in Voss, a total that also includes a silver for Travis Gerrits on Thursday in aerials.