It is still a matter of debate whether Klingons have two penises or simply have two urethrae in one gigantic penis. We’re just gonna have to see a naked male Klingon to be absolutely sure…

However, since they can easily mate with females of other humanoid species, I think the latter is far more likely. How would two penises even work anyway? Do Klingon women have two vaginas? And how would THAT work?