I have always understood them to be the same family, especially knowing two brothers who differ (1 Fargher, 1 Faragher) both claiming to be correct, and jealous of their names. I think it goes back to spelling being unimportant up to 20th century. When all said and done, the name Dougherty appears several different ways for one family in the Catholic church records, including different spellings for the same person in different colomns of the same page. Same principle I guess.