Did you mean provisional ballot?
Typically provisional ballots only come into play during an extremely close race. And they can usually be challenged.
Maybe we do ours differently. Granted they do come in play in an extremely close race, but so that no vote is eliminated the vote is counted if proper documentation is presented within ten days. Maybe that's why the SCOTUS smiled on Indiana.
They are kept in the clerk's office. Each in its own separate envelope. When the voter returns with proper identification, it is opened, counted and added to the final tally.