Questions on Revelation are extremely difficult to answer because they are so highly based on your view of Revelation, which is too hard to argue for in one post. I don't have the expertise to give a great answer to this question, but I thought I might as well give it a shot since no one else has.
As someone who tends towards a partial preterist position, I would be inclined to say that these were two real men. Who they were, I do not know (though I intend to by Greg Beale's Revelation commentary soon, and perhaps that will shed light on the question).
John Gill held that they represented a faithful few ministers of Christ down through the ages. He notes that the metaphor of the two olive trees is drawn from Zechariah 4:3, where they represent Zerubbabel and Jeshua, two faithful witnesses. This interpretation would likely be favored by many postmillenialists and amillenialists.
Sorry for such a bare-bones answer. I will post more if/when I know more.