You're not in a race with the voter since if you guess wrong and the person you were counting on to not vote, shows up to vote after you (or even before you, it

You're not in a race with the voter since if you guess wrong and the person you were counting on to not vote, shows up to vote after you (or even before you, it doesn't matter) -- then the game is up and there will be an investigation into the felony you just committed when two identical names show up. You have to be certain that there won't be two votes cast by the same person, so you can see how your probability of not being found out rapidly goes to 0. Even if you rely on the 60% turnout figure, after 3 fraudulent votes you're at a ~6% chance of not being caught.