In Norway and others in that region named boys after their father's given name. Arneson would be Arne's son, Pederson Pedre's son. This was taken as a "last name." That is why each generation has a different "surname" - the family is named after the son's given name. A guy with several brothers could each have a different last name. The Scots did a similar thing, when a Scot's family left the home of origin at least one letter of the surname was changed. Tod became Todd, Selby became Shelby, and so on. I don't know how many places this occurred but do know it was not uncommon.