The more the merrier! If everyone knows a confirmed mafia, but there's still a mafia left in CC's (or something similar), then today you should go for the CC's instead of confirmed. That sounds counter-intuitive, but let's think it through.
e.g. 1 confirmed mafia revealed by orc, 2 clears, 2 cop claims. it's day.
If you lynch the confirmed today, you're just going to get a clear killed. Having two clears is better than one, because they can discuss things with each other rather than having pressure mount on a single person. So you just lynch the CC's now. Confirmed mafia's either going to try to confuse you (don't fall for it, you already know he's a liar!) or just stay quiet/irrelevant (it's like he's dead or something! just what we want).
Of course, there are always exceptions in mafia; you always should think things through. Here are some things to think about: Can the 2 clears clear the cop somehow (as PR)? Is one of your clears a bad player that might ruin your chances of winning? If the confirmed mafia is a really good player, would it be worth taking him out first?