Unfortunately, age at death in Quebec records are not always accurate. There was 2 sons named Pierre and 2 sons named Jean-Baptiste. The first Pierre was baptized on 9 NOV 1744 in Forges-Saint-Mauriceand was later buried on 17 AUG 1745 in Pointe-du-Lac. The first Jean-Baptiste was born on 23 DEC 1742 in Forges-Saint-Maurice and died on 18 AUG 1745 in Pointe-du-Lac.
PDRH (Union #396421) confirms a second son named Pierre. There is a marriage contract between Pierre Girardeau and Marie-Josephe Caillé with notaire Jean-Baptiste Badeaux for 31 MAY 1783. The contract also confirms that Pierre is the son of Laurent Girardeau and Anne Trotaucheaux.
PDRH is a reliable source for the Quebecois Project. https://www.wikitree.com/wiki/Space:Quebecois_Project_Reliable_Sources
Nobody seems to have found a record for Pierre baptism around 1762 nor the marriage records.