I agree with all of Scott's suggestions, and I might add one more: enforce the minimum listening time even though you've heard it before.

Example, I judged a lot in folk, and since there were only a few hundred entries I eventually heard them all. But once you've done that, you can FLY through the judging, without having to listen to them at all. This allows the competitive types to quickly do what Juliana suggested, just judge "Same" over and over until you see the song you want to vote up. You could whip through dozens of match-ups in minutes. And Newport is another sparsely populated channel...maybe this is what's happening.

Still, I do see Brian's concern: as many votes as possible is a good thing.