Btw, I’ve personally been a site administer at a poll site for the Board of Elections, and just at my site I’ve encountered a voter walking in to vote only to find that someone else already signed in to vote in his name. The first signature was in the same name as the voter and the voter who walked in to vote showed ID proving he was who he said he is. I contacted the Board for instructions on how to handle it and they advised to let him vote. I made a notation on the signature book what occurred but I know it was never followed up by anyone afterwards.
And this was just at one random poll site I administered one year. It was never investigated, let alone counted as, voting fraud despite a strong possibility that it was just that.