Diphallia is also known as penile duplication (PD), diphallic terata, diphallasparatu, or diphallus. Colloquially, it is often called double dick.
More About Diphallia
It is believed that diphallia occurs at a rate of approximately 1 in every 5.5 million births. According to the Scandinavian Journal of Urology and Nephrology, the first case of diphallia reported occurred in 1609 in Bologna, Italy. Although each case of diphallia tends to be very unique, in most reported cases, one or both penises are capable of erection. Simultaneous erection and ejaculation have also been reported.