If you use the recommended high security setting a unique voting account is created for each voter which may include their email, name and other variables. This means the vote integrity does not depend on cookies or the IP address of the voter. People can vote from anywhere yet, if they attempt to vote again in the same ballot, even from a different location, the repeat vote is blocked.
However you can choose to let people vote repeatedly or a set number of times and still this will not corrupt the vote. This is because only the last vote from each person is counted in each ballot. It means you can run continuous ballots that can be relied upon.