Gemstone's "Cousin Dagobert" story

[Larry Giver]

    Gemstone's September issue of Mickey Mouse #268 has
a Donald Duck story "A Visit from Cousin Dagobert".
This "distant Cousin" Dagobert is just Donald in disguise.
Also, Donald has a neighbor "Smith" instead of his
usual neighbor "Jones".
    Anyway, I was surprised by the unusual name Dagobert
in this English language version, since Oncel Dagobert is
the German name for Uncle Scrooge.  Then I was very
surprised to see this name Dagobert in an old Barks story,
"Race to the South Seas".  I have 2 reprints of this story,
Walt Disney Donald Duck Adventures #26, July 1992, and
Gladstone's Carl Barks Library Donald Duck Adventures #14
(1995).    On page 2, panel 4, Scrooge's lawyer reads a
legal document to Gladstone, whereby Scrooge gives him a
sailboat.  At the top of this document I can read "Dagobert
Mc Duck".  How did Scrooge's German name get there in
this 1949 Barks story?
    The 1992 reprint only says this is a reprint of Barks' work,
but the Gemstone album reprint explains that Daan Jippes
and other artists at Oberon recreated this artwork and also
Barks' "Darkest Africa" story.  So it must be that the
English language version prepared from Jippes' art did not
notice this faintly legible heading on the paper Scrooge's
lawyer is reading.  But isn't Scrooge's German name just
Dagobert Duck, and not Mc Duck?  Is the Dutch name
Dagobert Mc Duck?