Complex sentence: Louis XIII's younger brother and younger son were granted the dukedom successively in 1626 and 1660, and since they had contemporaneous living descendants, there were actually two Bourbon-Orléans branches at court during the reign of Louis XIV.
Split into simpler sentences: Louis XIII's younger brother and younger son were granted the dukedom, successively, in 1626 and 1660. Since they had contemporaneous living descendants, there were two Bourbon-Orléans branches at court during the reign of Louis XIV.