No offense, ladies, but you're dangerous . . .
Now that you've found that out we'll have to remove you

So anyway, naming twins - if they share a sac they'll be same sex but ultrasounds aren't always all seeing so here are a couple historical examples...
Alexander Helios and Cleopatra Selene , twins of Marc Antony and Cleopatra.
Benedict and Scholastica , founders of the Benedictine Order .
Berenguer Ramon, Count of Barcelona and Ramon Berenguer, Count of Barcelona, born in 1054.
Waleran de Beaumont, Count of Meulan and Robert de Beaumont, 2nd Earl of Leicester, born in 1104.
Henry of Castile and twin brother Fadrique of Trastamara, born in 1333.
Henry III of Castile and Ferdinand I of Aragon, born in 1379.
James II (of Scotland) and Alexander Stewart, Duke of Rothesay, born in 1430.
Jeanne and Victoire de Valois (born 1556), twin daughters of Henry II of France and Catherine de' Medici.
Henry Vaughan, poet, and Thomas Vaughan, philosopher, born in 1622.
Ronald and Reginald Kray (born 1933 ), British gangsters.
Lava and Kusa, children of Rama and Sita Devi, Ramayanam (Hindu mythology).
Jacob and Esau, Biblical.
Perez and Zerah, Biblical.