Diphallia: an extremely rare congenital abnormality (birth defect) in which a male infant is born with duplication of the penis. This condition is estimated to occur in only one out of every 5 to 6 million live births. Diphallia is often associated with other abnormalities including gastrointestinal problems and other genitourinary abnormalities. The anatomical abnormality is often referred to as diphallus.
Mirshemirani et al. "Diphallus: Report on Six Cases and Review of the Literature." Iran J Pediatr. Sep 2010; 20(3): 353–357.