Okay, after thinking about this all day today, I've decided to rescind what I just told you, and make it so that if you guess more than one correct Clue in your Suspicion, you'll still have an equal chance of learning either Clue, regardless of whether you previously learned the Clue or not. So, in other words, if you already know the murder took place in, e.g. the Billiard Room, and you list the Billiard Room in your suspicion again, you may just confirm your previous suspicion without learning anything new.
Just my little attempt to make sure you guys are alive, awake, and paying attention.
As Josietta said, though, it really shouldn't matter. Just make sure that your next guess does not include a clue that you have already correctly guessed.