Infante D.João Manuel and Infanta D.Juana of Austria were also double cousins.
They were the siblings of Felipe II and Maria Manuela of Portugal.
Their only son was king D.Sebastião.
Philip II of Spain and his first wife Maria Manuela of Portugal were double cousins.
They shared four grandparents:
Philip I of Habsburg and Juana queen of Castle and Aragon Manuel
I of Portugal and Maria of Aragon
Their only child was Don Carlos.
Louis XIV and Maria Theresa were double cousins as well.
Henri IV of France and Navarre and Marie de Medicis
Philip III of Spain and Mariana of Austria
the sole surviving son of their marriage was the Grand Dauphin who married a Bavarian cousin and had three healthy sons.
Can anybody provide a list of marriages involving such persons? I believe that Holy Roman Emperor Francis II was married to one, and suspicions were raised that this was the reason for the birth defects of some of his children ...