I am glad that there is a cadre of interviewers. Were I the only person doing the job, I'd be tempted to take all clones of myself. I don't think I like too many of myself all in one place.
This is something that all of us need to be on the lookout for when we interview. Do I prefer this person over that person because we share personality traits, or is this person really more qualified?
I'm a big fan of more than just the hiring manager conducting interviews. Sure, it makes for a long day for the candidate, but multiple opinions can give you good insight.
Remember when you are hiring, you already work there. Therefore, how much need to you really have to hire another "you"? You may want to consider someone different in order to be able to accomplish more.
Of course, people need to be able to fit into the department. Personality does matter--just make sure you know your own biases before you start interviewing.