In Washington state, all voting is via paper ballots mailed or dropped off at a voting location. You sign them. People end up having different ballots because your ballot is customized for the district you live in (unique city, school district, county, state combinations is a reasonable size). They verify your signature. You can track if you ballot was received (it's inside an inner envelope) and if your signature was confirmed or not.

This feels safe, and as they have the original paper, they can revote - but they have all the ones in the district in a box somehow.