Is it possible to do that one machine? I don't see why not, but I have to assume the other machine is recommended for recovery reasons. Between upgrading an operating system and upgrading a ZCS suite there's potential for something to go wrong. If you have your original system intact, you not only have a backup copy, but also a machine ready to go in the even things don't go well.
Don't forget, "Is there a way" usually gets a yes answer in linux, although you may not like the description.
