I have located your ancestors in the book published by the Leduc Family Association!They are listed on page A35:
Joseph Leduc married 11 jun 1824 in Marieville, quebec, to Angelique Demers, daughter of Francois Demers and Marie Anne Foisy.They had 11 children, your joseph was married 24 oct 1848 at St marie de Monnoir, Quebec, to Adeline Giboulelau-Lafleur, daughter of Antoine Lafleur and Vitoire Remoil.
You are a decendant of Antoine Leduc. He is one of the origional four brothers that moved from France to Canada.please email me for more info on this line.
Jospeh's line - CharlesPierre-CharlesPierre-Charles then Antoine