Mike Wallace and Ed Bradley vs. Regis Philbin? As part of its May sweeps plans, ABC will schedule a special edition of the ratings phenom “Who Wants to Be a Millionaire” opposite CBS’s top-rated “60 Minutes” this Sunday. And in another assault on the competition, ABC plans to air an hour-long behind-the-scenes “Millionaire” special at 10 p.m. on Thursday, May 18 — opposite NBC powerhouse “ER.” What’s going on here? War of the networks? Not so, ABC executives tell Variety. “The thought was to try to maximize our assets,” ABC scheduling chief Jeff Bader told the trade paper.