You`re right in the sense of double counting but then you shouldn`t be referring to it as the magic number then if you don`t want to double count.Well, uh, yes? I’m not sure how this is difficult to be honest.
A magic number needs someone on the other end of you want to combine wins and losses. As the opponents change by round, you can’t really do that in the playoffs. The only number that matters is 11 wins. You can call it the Unicorn number if you want, but it’s not the same thing.