Clark: Herbert Clark Hoover
David: Dwight David Eisenhower
Earl: James Earl Carter
Gamaliel: Warren Gamaliel Harding
Herbert: George Herbert Walker Bush
Howard: William Howard Taft
Jefferson: William Jefferson Clinton
Rudolph: Gerald Rudolph Ford, Jr.
Trick question: no middle name: Theodore Roosevelt, William McKinley
Sidney, Sigmund, Stephen, Steven: Included to provide distraction from Sidney.
Orvan, Valentine: Included to fill things out and avoid obvious Presidential middle name such as Delano (FDR), Fitzgerald (JFK), and Baines (LBJ) and simply S. (Harry S. Truman). I also left out Walker (George Herbert Walker Bush), Wilson (Thomas Woodrow Wilson and Ronald Wilson Reagan) and avoided any earlier than McKinley.
The bit about "Joe the Plumber" not really being named Joe as that was merely his middle name is quite silly. Consider Thomas Woodrow Wilson and John Calvin Coolidge.