As Yamamoto-Genryuusai said earlier, that only 2 zanpakuto's existed in SS that come in pairs:
Sougyo No Kotowari:
Then why is Hisagi's zanpakuto the 3rd one?!?!?!
It's also paired, even if its connected with a chain (Ukitake's zanpakuto is also chained, so that isn't really an argument) And it's just like Ukitake's because in sealed form it's only 1 zanpakuto, but in shikai it's a pair.
Either Tite Kubo forgot this one, or Yama must be gettin senile (I can't believe Hisagi became VC without anyone knowing the true form of his shikai)