Would it be possible to put the election total of that machine on the card once the voter has voted it? That way if the card was not even programmed, a previous total would still be on the card.
I have thought about this issue a number of times in the past -- it came up again today at Virginia cert. What is the standard operating procedure if a voter comes back to the poll worker with their smart card and claims it isn't working? Well, we all know the answer to that: we burn them a new card. Problem is, the voter might be lying, and wants to vote again.
From a practical standpoint its this is really not a problem. I think everyone would agree this is a pretty ineffectual way to stuff a ballot box. I do worry a bit about having to explain this reasoning to John Stossel though.
The only practical suggestion I can think of is to timestamp the voter cards when the ballot is cast. Inserting a voted card would pop up a message saying that the card was voted and when. A poll worker would then know that the ballot was just cast.
For now I suspect we will continue to pretend the issue doesn't exist. It is worth thinking about though. Any other practical suggestions on how we might handle this are welcome.