It is possible that the name Dobbs could be transcribed as Duff in some records, e.g. Census Records. It is most often transcribed incorrectly as Dabbs or Dodds but some of the older handwriting could have the "bb" confused with "ff." However, Duff is not a variation of Dobbs. They are two distinct surnames. The Scottish etymology of the name Dobbs is a "pet" name for the given name Robert and can also be "son of Robert." The name Duff derives from Gaelic Dubh meaning dark black used as both a nickname and a personal name. In Scotland, it is usually a descriptive name for a dark-haired man. It is also a short form of Duffin and a variant of Duffy. See also "Dow." I cannot find any connection between the surname Dobbs and Duff.
