Yes, it was rhetorical. But, it seems like it could happen.
It could. In fact, I’ve seen it happen. I don’t think it was intentional, but I was at the sign in table when one of the ladies who was minding the book checked off the wrong name. That is the reason that (in Mequon, at least) we have 2 clerks on the books at all times. In any case, somebody checked off the wrong name. When the person came into vote, one of our books said that that person had already voted.
After a little kerfluffle, we back tracked and found the mistake. If we hadn’t been running 2 books, that voter would have been out of luck.
Now that the voter has to sign one of the books, I don’t think that it would be as easy to make such a mistake — UNLESS it is intentional. The voter would not sign over the wrong name, unless he/she means to.