Hmm, that certainly colors a rumor I've heard about Apple. That they'll have two or three teams compete on a new product... but they won't tell the teams that they have competition until final demo day.
I don't think I've ever heard that about Apple, though, at least as standard (even unofficial) operating procedure. There's sometimes competing internal concepts -- the iPhone's operating system probably being the most famous example, with Scott Forstall's team basing theirs on OS X and Tony Fadell's team basing theirs on Pixo OS -- but I don't think they were being kept secret from one another.
Awful thing to do to engineers, but you can understand why management would do it and why they wouldn't want to demoralize the secondary team by telling them.