Ducati only seem to do 2 speedos - KmPH and MPH.
All the MPH ones I've ever seen have the 55 marked on it, and no KMPH markings on them either - this is really annoying when you go abroad as I've never any clue how fast I'm going and I know that MPH is faster than the same figure in KMPH
Again, all the KMPH ones I've seen don't have MPH markings on them either.
I guess this is to standardise their output of dial faces. It doesn't make any difference to us in the UK if 55mph is marked (it just looks weird) but they can use the same speedo for different countries.