It's the same in England, unsurprisingly because the American handwriting would derive from it.
It normally is totally correct to use one capital F (the duplicates caused by Ffreckes and Freckes and Ffootes Footes both of of Ffifehead or Fifehead Neville have been numerous !) However, in this case, the family adopted the 'affectation' of using a double ff for their name
See RJs note on the profile