Louis Alphonse, Duke of Anjou
Their father has conferred upon them the historic French titles of, respectively, Duke of Burgundy ("duc de Bourgogne"), and Duke of Berry ("duc de Berry"). (In Spain, the twins are "Don" Luis and "Don" Alfonso de Borbón Vargas). Prince Louis, as Legitimist Dauphin of France, is expected to succeed his father as head of the French royal house, the senior Bourbon/Capetian line, in Legitimist reckoning. However, under Spanish law, and assuming Felipe VI does not in future father a son, the Spanish crown will be inherited by his elder daughter Leonor, Princess of Asturias, who will become queen regnant, and if Felipe does have a son, that son will inherit the Spanish throne regardless of the genealogical seniority of the Anjou branch. Louis and Alphonse were baptised on 5 September 2010 at St Peter's Basilica in Vatican City. Louis' godparents were Arancha Martínez-Bordíu and Francisco D'Agostino and Alphonse's were Amparo Corell de Trenor, and Lorenzo Perales.
Madame Royale
It was similar to the style "Monsieur", which was typically used by the King's second son. Just as Gaston, duc d'Orléans (1608–1660), the second son of King Henry IV of France (1553–1610), was known as " Monsieur", Elisabeth of Bourbon (1602–1644), the eldest daughter of Henry, was known before her marriage to King Philip IV of Spain (1605–1665) as "Madame Royale". After her death, the title was borne by her younger sister, Christine Marie of France (1606–1663), until her marriage to Victor Amadeus I, Duke of Savoy (1587–1637).
The most famous holder of this honorific was King Louis XVI of France's eldest daughter, Marie-Thérèse-Charlotte (1778–1851), the only one of his immediate family to survive the French Revolution. She later married her cousin, Louis-Antoine, duc d'Angoulême (1775–1844), and played a prominent role during the Bourbon Restoration.