My opinion is there is no such thing as an "Octopus" since A) it only has one hose, not eight (LOL) and B) a second stage is a second stage. Your primary second stage is the one in your mouth and your secondary second stage (or what some people inexplicably refer to as an "octopus") is the other one that’s not in your mouth. Ideally, you would just have 2 of the same one so it doesn’t matter which one is in your moth at any given time.