From Anomalies and Curiosities of Medicine by George M. Gould and Walter L. Pyle:
Wells a describes Mrs. B., aged twenty, still alive and healthy. The duplication in this case begins just above the waist, the spinal column dividing at the third lumbar vertebra, below this point everything being double. Micturition and defecation occur at different times, but menstruation occurs simultaneously. She was married at nineteen, and became pregnant a year later on the left side, but abortion was induced at the fourth month on account of persistent nausea and the expectation of impossible delivery. Whaley, in speaking of this case, said Mrs. B. utilized her outside legs for walking; he also remarks that when he informed her that she was pregnant on the left side she replied, "I think you are mistaken; if it had been on my right side I would come nearer believing it;"--and after further questioning he found, from the patient's observation, that her right genitals were almost invariably used for coitus.
(the name Mrs. B. refers to Myrtle's married name, Bicknell.)