Voting for the same person all three times doesn't disqualify those votes, but only the first vote will count. The way that LJ's tallying votes means that a voter's second choice vote (and third choice, if it comes to that) only gets added to the totals once that person's first choice candidate has been eliminated from the running.

It's not hurting Jameth to have his voters waste their extra votes on him, but it's not actually helping him, either. It would be completely counterproductive to follow that example if there's more than one candidate you'd be happy to see win, though, since you can't help your first-choice candidate that way and can only hurt your potential second- and third-choice candidates in the event that your first-choice candidate gets eliminated from the running.