Structurally/developmentally, the penis is just an enlarged clitoris (fun fact: the line down the underside of your penis and around your scrotum, called the raphe, is where what would have been your labia grew together), so the case of a futanari with a penis growing where the clitoris would in a baseline female makes some degree of sense. Some people thus complain about futanari structured with both a penis and a clitoris.
But oddly enough, there is diphallia, the medical disorder of having two penises, and there have been cases documented where the two are situated similarly to the image, one atop the other. So this is actually a plausible construction!
There are parallel conditions where a male may have more than two testicles, or a female may have multiple vaginas and/or uteruses (in 2006 a UK woman had triplets: identical twins that implanted in one womb, and a third child from the other), but I'll stop killing catgirls now.
