This doesn’t work the same way in every state. In my county of CA you only send back a single envelope with the ballots folded over. Instead there is a serial n

This doesn’t work the same way in every state. In my county of CA you only send back a single envelope with the ballots folded over. Instead there is a serial number you can tear off to validate that the ballot was counted. So it’s not doubly secret in the way you describe: https://elections.cdn.sos.ca.gov/vote-by-mail/pdf/guidance.pdf https://elections.cdn.sos.ca.gov/vote-by-mail/pdf/guidance.p...