I'm asking if they are more than one person, or not (which is the part I liked second least in the finale)......because if they aren't, he doesn't have to save him, he's there (as Stephen realized in the previous episode, if Marc is in him, he can do what Marc does.....and yet). If they are one person, well, a lot of that didn't make sense.....If you are asking for logical consistency around magic, you are unlikely to find it.
Within the system they have laid out, I'm asking for internal logic (that's very important for magic in fiction, as many writers have told us over and over).