Yep.
It was only supposed to switch half of the Republican votes to Democrat, not all of them.
Oopsie!
It wouldn't surprise me if that's what really happened. They got caught because a GOP candidate for state rep. carefully looked at what the final ballot choices read before hitting "cast ballot" on the screen. Probably a lot of older voters don't even look at the numbers, they're just relieved to finally get to the end of a long touch screen ballot and it "cast ballot" when it asks voters to review all the choices they made.
There was a bunch of useful idiots on the Illinois board back in 2010 who found nothing suspicious when Bill Brady had been polling 8 points AHEAD of Quinn in suburban Cook County the week before the election, but on election day, he lost suburban Cook and got a lower percentage of the vote in my pct. than McCain had gotten in 2008 at the HEIGHT of Obamamania (32% for Brady vs. 34% for McCain). They retroactively decided "Brady ran a terrible campaign" (Funny, a week before the election, they said his campaign effort had been excellent)