I think that Feerik's rollover/voting is all messed up.  I know that I've had times when I know that roll-over has occurred since I am able to "work" and I will vote for someone right after that.  I get lost doing something else and come back to DVing, forgetting that I've already voted for that first person... so I vote for them and I did not get the message of "you've already voted for them"

And to further concentrate on your question, that's happened to me as well... more names showing up on the 'last 100' right after roll over than what is showing on my page.  I probably have just 'tuned it out' and don't notice it as much anymore.