The Moucheaud brothers are two more mill hands at Ackerman & Hook. They are French-Canadian, and "they were inclined to be excitable, talking in loud voices and arguing with each other, or anybody else for that matter" (9. 3). Ox jokes that in English their name would "probably come out 'much odd'" (9. 3). Good one, Ox!
The Moucheauds aren't bad guys, and they're more than willing to help Tom with his barn-raising when he asks. They even bring extra lumberjacks to help. However, they serve as contrasts to Tom's character because they sort of just bumble about life while Tom pursues a very specific goal. We can see the contrast in moments like this one:
[Bancel] wondered if Tom could lend him the price of a two-cent stamp. What he wanted to write to his Prill [the girl he's smitten with] wasn't the kind of message you would like to put onto a postal card. Tom happened to have a five-cent piece in his pocket that day and he gave it to Bancel, who promised to give back the change. Bancel Moucheaud was always happy-go-lucky in his money dealings. You couldn't get annoyed with him, though, because he would as soon lend Tom a two-bit piece as borrow a nickel. The trouble was he never seemed to have any money himself, not in his pockets at any rate. (33.9-10)
While Bancel is absent-mindedly broke and spending his time pursuing a girl with what sound to be risqué love letters, Tom is worried about saving money, building a barn, and bettering his life. He's got no time for girls or booze, the latter of which the Moucheauds take in liberally at the mill's Christmas party and at the barn-raising. Well, to each his own.