Board Thread:General Discussion/@comment-4957813-20131130185522/@comment-24282510-20140601002145

Benter wrote:

Katen Kyōkotsu and Sōgyo no Kotowari manifest them self as 2 separate spirits. Hisagi's zanpakuto has only one spirit. For the latest version of Zangetsu it is unknown.

Non canon.

Though i wonder if ambidexterity has any role in it? It can't be power alone has if that were true most of the captions would have dual zanpukatos.