They were probably thinking next year, they can call the new one Titan XPP. Historically, their naming conventions for GeForce cards haven't been super consistent either.
Really? The first number is always the major release and the second number is always the line from what I can recall? It's pretty high up there in terms of naming consistency.
I don't mean that kind of branding, I mean the kind of rebranding where for example the take the same chip that's in a GTX 680, and re-release it as a GTX 770.