This Cuthbert Ducharme was the son of Joseph Ducharme and Julie Sévigny. He was born on Sept. 19, 1842, and died on July 11, 1843, as stated in your message.
Although Cuthbert was not a French name, it is found quite regularly in the Lanaudière area, where Ducharme lived (including St-Ambroise), because of James Cuthbert, a British officer who became landlord and was quite popular.
However, I don't believe that Cuthbert «Papineau» Ducharme has any relationshiph with these Ducharme. He is from a completely different family.