I like the idea of one inside the wall, and one outside. It does mean you can't use those nifty double track hangers, since now you'd have two completely separate lines of track...but it would also mean you wouldn't be tied in to making both doors the same size, and there would be no problems sealing (well, no more than any other sliding door, at least).
Then the only other "gotchas" would be getting the inside door to clear anything you already have mounted on the wall there, and not whacking the man door off its hinges with the door that slides through its "swing" space any time you forget to close it first...?
Then the only other "gotchas" would be getting the inside door to clear anything you already have mounted on the wall there, and not whacking the man door off its hinges with the door that slides through its "swing" space any time you forget to close it first...?