Yes I agree two single cruises, northward and southbound, with the same itinerary, don't appeal. I just like to draw attention to low or no single supplement offers. I think it was HAL which has just cancelled Denali land travel component of their cruises plus land. Passengers with cruises booked which were to join land travel weren't happy.
I'd love to return one day via Alaskan Marine Highway, plus truck camper hire.