Bouillon speaks of a negress in Guadeloupe who bore twins, one a negro and the other a mulatto.

She had sexual congress with both a negro and a white man.
Delmas, a surgeon of Rouen, tells of a woman of thirty-six who was delivered in the hospital of his city on February 26, 1806, of two children, one black and the other a mulatto.

She had been pregnant eight months, and had had intercourse with a negro twice about her fourth month of pregnancy, though living with the white man who first impregnated her.

Two placentae were expelled some time after the twins, and showed a membranous junction.

The children died shortly after birth.
Pregnancy often takes place in a unicorn or bicorn uterus, leading to similar anomalous conditions.