The Battle Rounds continue tonight, and the action isn’t confined to what’s inside the ring. It’s interesting, so far, how often some of the mentors have given advice that seems to conflict with the established practices of the star judges and team leaders. And, for that matter, how the initial airings of contestants have made some battles really tough ones, and others more like musical slam dunks. Each judge, I suspect, is stacking his or her own deck, selecting songs and duet