A baby boy born with an extra penis on his back has had it amputated in a successful operation in Hebei, China. His parents, a farming family, apparently did not notice at first, but soon took him to hospital on realising his extra endowment. See the infant and his extra member in complete detail here.
The medical diagnosis proffered was that a parasitic twin (a condition where twins fail to develop normally in the womb and one becomes conjoined or reabsorbed, etc.) developed partially, with only the genitals forming completely, and subsequently became attached to the back of the surviving foetus. The twin cum penis also apparently had one complete testicle, the other having been lost.
As the extra penis was apparently attached to the spine and nervous system of the infant, the three hour long operation to remove is posed a high degree of difficulty, but was completed successfully, with the baby showing no signs of nerve damage. He is expected to be discharged in two weeks.