It must be difficult for an American President to remember the names of every foreign politician at summit meetings.
During the 2011 Republican presidential campaign Mitt Romney (he of a thousand gaffes) took part in a presidential debate. Introducing himself, the CNN presenter said "I'm Wolf Blitzer and yes, that's my real name."
Mitt Romney replied "I'm Mitt Romney—and yes Wolf, that's also my first name." Apparently forgetting that his first name is actually Willard - Mitt is his second name.