Forum:Is it possible to have TWO Zanpakutō? (legitimately)

Okay. Ichigo used Rukia's Sode no Shirayuki in it's sealed state the entire first arc of Bleach. Tōsen uses the Zanpakutō of his fallen friend but they never explain if he can use/create his own, and Aaroniero Arruruerie stole Nejibana from Kaien to use with his Zanpakutō Glotoneria. What I want to know is since Tosen and Aaroniero "took" their zanpakutō from fallen shinigami, has there ever been any explanations about using somebody else's Zanpakutō? (Manga or Anime)