Republicans have achieved this mandate 16 times since Lincoln. Grant twice, McKinley twice, Theodore Roosevelt, Taft, Harding, Coolidge, Hoover, Ike twice, Nixon, Reagan twice and Bush I.
I guess we have to throw in Democrat Sam Tilden, got a majority of the electoral vote in 1876.
Strange that one of the few Democrats to break the 50.1% barrier didn't win.