Complex sentence: Of the two, the elder brother Joseph (J.-H. Rosny aîné) is somewhat better known and many of the joint Rosny works are incorrectly attributed only to the the elder brother.
Split into simpler sentences: Of the two, the elder brother Joseph (J.-H. Rosny aîné), is the better known. Many of the joint Rosny works are incorrectly attributed only to the the elder brother.