I mean, it kind of is? Not everybody has the same number of legs, so the model should turn out people with just the one as often as the real world does, unless the prompt tells it different.
Never seen anybody with quite so many knees though.
Yeah, however it wasn't doing that "intentionally" (to the degree that a bunch of matrix math has intent) - I think it's pretty clear that the missing leg and the extra knees are the same category, the same one as extra fingers and clothing parts that just taper in and out of existence, etc.