I'm sure he is not the only reporter not using his real name. I mean, Wolf Blitzer? C'mon. lol
Interesting question, and one I'm trying to check into, but have found little.
According to
americanprofile.com, Wolf Blitzer is Mr. Blitzer's real name.
According to
Snopes, Geraldo Rivera's birth name is Gerald Riviera (not Jerry Rivers, as the urban legend goes).
Some female reporters use their maiden name, even if they use their married name in their everyday life. And I'm sure some reporters have ethnicized their names to sound more exotic.