It will grow just fine. Do notice one side is stronger than other. Why not let the tree put all its energy into growing one central leader. Chestnuts are supposed to be central leader trees. They will have the best nut production that way. I mean just look at nursery stock very few trees species have multiple trunks. Cut extra trunks or branches when young meaning small. Small cuts or wounds heal faster than large ones. Out in my oak forest when I see a two trunk tree, I usually cut one side down. That's the same as thinning the trees around certain trees to help them with growth and production.  I do have some big two trunk oaks that work great for a ladder stand.