You know the doors that are in hotels that pass between rooms. They make it easy to rent two rooms side by side, one for kids, one for the parents...or co-workers traveling to a meeting etc. I got a question via email asking how to approach this. The issue expressed was that Revit won't let you put two doors on top of each other. They want to list two doors in the schedule (one for each side) so the more or less obvious solution of showing both panels and swings in one family didn't cut it.
One solution is to edit the door family and eliminate the Opening element and replace it with a void instead. This allows you to adjust the depth of the void so it only cuts one half of the shared wall. Place two doors and align them...voila, done. If you make this an instance parameter driven option your regular single flush door type could pull double duty, cutting all the way through a wall or only half way.
Another approach could be a single family that uses two nested (and Shared) families. The door could be assigned to the Generic Model category so the assembly doesn't schedule in a door schedule, the nested shared doors (assigned to the door category) do instead. Alternatively the category could be assigned to doors too but you'd either have to filter out the assembly or the individual doors because you'd have an "extra" door.
Whatever solution we use we do have to consider how "we" schedule doors and how the product is dealt with by a manufacturer. Since the frame has to built to accomodate two panels it might actually be better or correct to create a single door family that just happens to have two panels. Everything is a bit trickier the deeper you look at the question, at least when you aren't just concerned with what a door looks like in a plan view drawing.