It's only fairly recently that there's been an attempt to standardise spelling of names and keep accurate, traceable records.
My French L'Estrange family eventually became Streing then Strang.
German ancestor Buechele went to America and generation by generation the surname became Buechle, Beeghley, Beeghly, Beighley, Beachley, Beechly, Beekley, Beeckley, Peachley, and many more variations...
Swiss Zuggs were Zaugg, Zug, Zook.
Welsh Rhys evolved to Rice, Roice, Royce.
Dutch van Ditmarsen ('of Ditmars') later Ditmarsen, Ditmars, Ditmarrs.