Crypto identities are identities, as much as human names or Social Security numbers. If you know who the identity represents, then you know that human's transaction history for all time on that blockchain.
Ballots do not have any identifying information, intentionally. There is no tracking number or possible mechanism to de-anonymize a ballot back to the human who cast it. Notably, there is not even a unique identifier for a single ballot that could potentially be used to identify a person.
Most importantly, there is no value that is unique to the ballot that I can use to verify that I am indeed the person who filled it out, so some nefarious organization could threaten me or my family to produce proof of how I voted. Or pay me, or influence me based on the outcome.
So there is no "identity" that you can record in a blockchain to prevent that identity from casting two ballots in the same election.
Ballots do not have any identifying information, intentionally. There is no tracking number or possible mechanism to de-anonymize a ballot back to the human who cast it. Notably, there is not even a unique identifier for a single ballot that could potentially be used to identify a person.
Most importantly, there is no value that is unique to the ballot that I can use to verify that I am indeed the person who filled it out, so some nefarious organization could threaten me or my family to produce proof of how I voted. Or pay me, or influence me based on the outcome.
So there is no "identity" that you can record in a blockchain to prevent that identity from casting two ballots in the same election.