[grzm]

In my experience in the US, you have a registered polling station where you are allowed to cast your ballot. When you arrive, they cross your name off the list. If I'm only allowed to vote in one location, and that location only allows me to vote once, that should prevent double voting, even if I'm not who I say I am. Or rather, I'm not going to vote twice as the same person.

Is this the case across the US?

Whether the voter registration rolls are up-to-date, that's another matter as well. And double voting is only one type of fraud.