10 ILCS 5/24-18
A voting machine which passes all of the qualities required by this Article may be supplied, in addition, with any recording or photographic device on which the votes registered on the mechanical counters will be separately recorded or photographed. When a machine is supplied with a recording device which automatically registers the votes cast for candidates, questions or propositions, on separate recording sheets one copy shall be removed at the close of the polls to record the vote cast for each candidate, question or proposition and the other recording device shall not be taken out or examined by the election officers who make returns from the precinct, but such machine shall be locked with such device therein and so remain until the record made by such photographic or other device is removed and prepared for examination by the official canvassing board having charge of canvassing the returns of such election or primary, and the official canvassing board shall compare the totals as shown on the official return sheets with the totals as shown on the photographic or other device, and see that both such totals are the same. In case such totals are found not to be the same, such canvassing board shall summon the precinct election board which made the returns and together these two official bodies shall make the necessary investigation to ascertain the true facts and shall then correct the official return sheets as necessary. The record provided by such photographic or other device shall be filed along with the official return sheets by the officials now charged by law with filing and preserving the official return sheets, and shall be kept so filed for the same length of time as the law now provides for the filing and preservations of the official return sheets.
10 ILCS 5/24-18