The one time unique ID must be recorded *on the ballot* so that when the
ballot is scanned into the vote tallying computer system, it is there
*with the ballot data* for inclusion in the database of all votes,
**and**, so that it is still there in any possible recount of the votes,
***and***, this must be done while the voter is waiting in the polling
place.
I think these are requirements for voter verification to be meaningful.
I don't think they are easily met, just that they are requirements of
voter verification that uses one-time unique ID on a paper ballot.
If one accepts 'electronic ballots' other things are required, but I
was writing about voter verification of paper ballot elections.