You're right they're normally amputated, but diphallia rarely occurs without a whole bunch of other serious defects. Doesn't seem related to intersex stuff.

Diphallia is usually accompanied by systemic anomalies; their extent varies, ranging from no associated anomaly to multiple anomalies including urogenital, gastrointestinal and musculoskeletal systems.[1][8] Penile duplication also varies from a single penis with double glans to complete double penises.[6] The meatus may be normal at tip of glans, hypospadiac, or epispadiac; the scrotum may be normal or bifid.[14] True diphallia is more likely accompanied with associated anomalies and malformations compared with bifid phallus.[1] Infants born with diphallia have higher death rate due to infections associated with anomalies

Cw big very gross picture right away https://en.m.wikipedia.org/wiki/Diphallia