Allen Garfield's birth name is Goorwitz, Allen.
Gil Garfield's birth name is Gilbert Garfield.
Yes, if a son is given all the same names that his father has, and his father is not already a 2nd or 3rd, then the son may be called 2nd, or Junior. If the father is James Allen Garfield, and the son is named James Allen Garfield, then the son can be called either James Allen Garfield II, or James Allen Garfield, Jr. If the father is James Allen Garfield III, then the son is James Allen Garfield IV. If James Allen Garfield I and James Allen Garfield II are no longer living, then James Allen Garfield III could call himself James Allen Garfield, Sr., and his son James Allen Garfield, Jr.
Allen Ludden's birth name is Ellsworth, Allen.
Allen Coage's birth name is Allen James Coage.
Allen Turing's birth name is Thomas Price Allen.
Byron Allen's birth name is Byron Allen Folks.
Dayton Allen's birth name is Dayton Allen Bolke.
Dede Allen's birth name is Dorothea Corothers Allen.
Devin Allen's birth name is Devin Allen Beach.
Domenick Allen's birth name is Domenick Allen Capaldi.
Fletcher Allen's birth name is Frankie Fletcher Allen.
Gilbert Allen's birth name is Gilbert Stafford Allen.