Board Thread:Theories and Speculation/@comment-25645405-20150719020101/@comment-9782468-20151130125723

@Zach, Orochimaru basically said he'd been looking for it. He said something like, "This is the blade of Totsuka! So, you've had it all this time, Itachi."

That kind of implies to me that it was the only one. I think Itachi just somehow assimilated it into his Susanoo, I don't think any shinobi, lucky or not, can just manifest it.