I, as resident linguaphile in my school, argue with everyone about proper use of words and pronunciation... it is my belief that the word "résumé" is pronounced with an acute accent over both 'e's. And while multiple dictionaries back me up on this, a friend of mine holds steadfastly to the belief that the dictionaries are wrong. He says that having an accent over both 'e's changes the pronunciation of the word. So my question is - aside from the dictionary, is there some definitive source I can use to prove my friend wrong?

Thanks,
Josh.