My only problem with having two rounds of votes is that it could be the same majority that chooses both skill trees. In other words, more people would get two skills they want and less people would get at least one skill they want.
I agree with Ayvah... as it is, the group that voted for the winning skill tree, already got what they wanted. Also picking the second placed skill tree, means that from the remaining voters, the largest group also got what they wanted.
Having two separate votes could mean that those who voted for the winning skill tree, got their second favorite as well... and everyone else got nothing.
So imho, one vote to decide both skill trees is the fairest solution.
