Mikael Kingsbury defeated fellow Canadian Philippe Marquis 20-15 in the men's big final for his first world dual moguls gold after two runner-up finishes.
Marc-Antoine Gagnon made it a Canadian podium sweep by beating Sho Kashima of the United States in the small final.
Dufour-Lapointe lost to American Hannah Kearney in the women's big final by a score of 29-6.
Yulia Galysheva of Kazakhstan edged Justine's younger sister Chloe Dufour-Lapointe 18-17 for the bronze medal.
Canada's four medals on Monday capped a stellar run for the country's moguls skiers at the world championships. Justine Dufour-Lapointe, who's from Montreal, won gold in the women's singles event on Sunday, while Kingsbury, from Deux-Montagnes, Que., took silver on the men's side.