FPNs should be given to first-time offenders only, but Detective Inspector Montford of Greater Manchester Police admitted that administration errors had led to some shoplifters being given two or more notices.
"Within 24 hours of issuing the notice, the officer is supposed to log it onto a database so that serial offenders don't get notices, but on several occasions this was not done, leading to more than one notice being issued," said Montford. "This has now been rectified and all penalty notices are being logged properly."
Penalty notices have attracted criticism from MPs, the Magistrates' Association and high-ranking officials within the police force who have questioned their effectiveness and inappropriate use by the police.
Last December Justice Secretary Jack Straw launched a review of the FPN system, the findings of which are due to be released in March.