I like how having two dicks means he (of course) has both a boyfriend and girlfriend. Also the bullshit about needing to cum multiple times a day or else he experiences pain. "But honey, I NEED TO CUM... MY TWO DICKS DEMAND IT OR ELSE!"
Diphallia is a legit medical condition. It does happen, but it's super-duper rare. Extra breasts, ambiguous genitalia, or extra testicles are way more common. True diphallia cases have the penii side-by-side, never one above the other (that'd be a fake).