I was a poll watcher in Kenosha. (I drove up from Lake County, Illinois) My precinct had UW-Parkside in it. We saw several hundred students who were bused in and then registered and voted using nothing more than their student IDs (which doesn't have an address on it) When we protested, we were put in contact with the head of the state board of elections, who's a democrat. He told us that they could vote, as long as they were on the list of students who lived in the dorms.
There had to be at least 700-800 students who voted this way, all in one precinct.
Unfortunately, that is the law in Wisconsin - sucks doesn't it? There's no way of knowing how many of those kids voted absentee from their home states.