Millie and Christine McCoy (or McKoy) is Siamese twins pygopages (bound by the sacrum).

Born slaves in North Carolina in 1851, they were sold to a man of circus, J.P. Smith, with the birth, but were then kidnapped by a rival who took them along to England.

When the country abolishes slavery, Smith went to England to recover the girls and brought with him them mother, of which they had been separate. His wife and itself dealt with their education and 5 languages learned to them, to play of the music and to sing. They made career under the name of Rossignol with two heads and turned with the Barnum circus. They died into 1912 of tuberculosis, at 17 hours of interval.