My latest S-Type had a dreadfully worn and torn driver's side door seal and the hunt was on in local breakers yards to find an acceptable replacement. Unfortunately, all the cars I saw had the same sort of damage to the door seal.
Flicking through the JEPC, I noticed that the same seal was shown for either side of the car. Went and got a perfect seal from the passenger side of the first scrap car I saw, in perfect condition and, best of all, fits my driver's side aperture perfectly :)
So, if you need a replacement door seal, then either side of the car will do, bearing in mind that the driver's side always takes a much greater hammering than the other doors.