All those dust votes add up and they count as long as the total vote breaks the dust threshold.
The way I see it (and I'm open to hearing all opinions on this) is that no matter how large or small your vote is when you see good content it's when you should cast a vote. If the content is good enough that someone feels it's "undervalued" and deserves more rewards (the point of the contest) why wouldn't you want to help give those rewards? It's 2 votes out of at least 70 you get in a week. Will see if other have an issue with the upvote, but do know the judges have questioned why people don't vote many times.