But you did that by making a big, surprising claim for which you haven't provided any evidence. You might not intend for that to be the main thing people focus on, but they are right to be both interested and skeptical! If true, it's a big deal.
The closest thing I could find is this (https://www.thenation.com/article/archive/voters-predominant...), which was attributed to 'human error' rather than fraud, and was resolved by allowing the affected voters to cast provisional ballots. 'Human error' is a vague explanation, and for all I know it was a coverup -- but the onus is on you to provide some positive reason to believe that. Surely there were plenty of people motivated to investigate this, so it would be surprising if a bullshit explanation was just quietly accepted and no further public attention paid.
Not sure why your OG post is still up.
Voter ID solves a non-existent fraud problem and does so by making voting harder.
The idea that if we had paper ballots with walk-in only, ID-verified votes, that Trump and Fox News et al wouldn't have launched a coup attempt, or wouldn't have gotten nearly as far, is pretty laughable. In fact we have Trump on the record saying as much: "It doesn't matter whether you win or lose, you have to fight like hell."
Let's take your scenario. In fact there is a way to verify which vote was correct (and it's used already) which is to match the signatures between the voter registration and the ballot.
This is sufficient except in cases where the registration itself was fraudulent, which would have required 1) having someone's ID at time of registration and 2) intercepting the mail sent to their ID- or utility-bill-confirmed mailing address.
An attacker who could achieve that could also have achieved just walking into the polling place to achieve the same false vote.
Any attack is extremely expensive to do at any meaningful scale, and all scaled attacks are detectable by simple statistical sampling.
If meaningful amounts of tampering were detected by statistical sampling then you can obviously re-run elections with tighter controls, more burden, lower turnout, and a generally-less-representative result, which is why we start with a more inclusive system. This can and does actually happen. Whether it's necessary is literally 100% statistically knowable through basic sampling.