Nothing about the US system is particularly geared to prevent double voting.
I get that you don't have a federal register (something you should really fix tbh) but requiring manual registration when you could, oh idk, simply register people when they are born and then later automatically provide them a unique ID they can vote with? (I'm not even talking a government ID for the purposes of identifying yourself to law enforcement and stuff, I'm talking even just a voter ID for the sake of voting only)
Then have part of the number in that ID identify the state you're from if you want to prevent crossing borders to double vote (kinda like how credit card numbers have that info on them).
It's what they do here anyway, I've had an ID since I was like 4, and it's with that document that I and everyone else votes.
Though I know the US is probably too anti-democratic for this and none of the parties in power want to change jack.
You might not have heard of the formats but you've definitely listened to them. For example, Youtube has only served audio in aac and opus for years now. Most instant messaging apps also use opus during calls to reduce bandwidth usage. And those are just some big examples. Basically almost any online service has dumped mp3 in favor of aac and opus since they're better in every way (in the sense that they have better quality at the same bitrate as mp3, so you can reduce the filesize by a lot and still preserve the same audio quality)