Frederick Douglass does in fact have a middle name but it is in his real name. After escaping slavery he changed it to what he is known by, Frederick Douglass. His actual name is Frederick Augustus Washington Bailey.
John Adams did not have a middle name, his full name was John Adams Jr. I have read two separate things one says John Quincy Adams was the first President with a middle name, another says John Quincy was his full first name and he didn't have a middle name, I don't know which is accurate.