i think keeping the names hidden until then end of the competition is a great idea ....

first off it keeps the creator and the creation seperate.... it is cool not knowing who did it..
also it keeps whatever feeling the people who are voting on the sigs have toward the creator seperate so there is no favortism going on because you like the person or not(providing the creators doesn't tell anyone... i know they won't do something like that) and thus you can judge freely without having any emotional baggage....

as for keeping track it not that hard, you just keep all the info from the rounds and then cross refference it with what you have at each round submission....

i also think it would be a great idea to post all the sigs from each round with the creators name attached to it at the end of the compitition so it is easy to compare and contrast the differences in the creators work in each round.... and so on.