10 ILCS 5/10-6.2
The State Board of Elections, the election authority or the local election official with whom petitions for nomination are filed pursuant to this Article 10 shall specify the place where filings shall be made and upon receipt shall endorse thereon the day and the hour at which each petition was filed. Except as provided by Article 9 of The School Code, all petitions filed by persons waiting in line as of 8:00 a.m. on the first day for filing, or as of the normal opening hour of the office involved on such day, shall be deemed filed as of 8:00 a.m. or the normal opening hour, as the case may be. Petitions filed by mail and received after midnight of the first day for filing and in the first mail delivery or pickup of that day shall be deemed filed as of 8:00 a.m. of that day or as of the normal opening hour of such day, as the case may be. All petitions received thereafter shall be deemed filed in the order of actual receipt. However, 2 or more petitions filed within the last hour of the filing deadline shall be deemed filed simultaneously. Where 2 or more petitions are received simultaneously, the State Board of Elections, the election authority or the local election official with whom such petitions are filed shall break ties and determine the order of filing by means of a lottery or other fair and impartial method of random selection approved by the State Board of Elections. Such lottery shall be conducted within 9 days following the last day for petition filing and shall be open to the public. Seven days written notice of the time and place of conducting such random selection shall be given, by the State Board of Elections, the election authority, or local election official, to the Chair of each political party, and to each organization of citizens within the election jurisdiction which was entitled, under this Code, at the next preceding election, to have pollwatchers present on the day of election. The State Board of Elections, the election authority or local election official shall post in a conspicuous, open and public place, at the entrance of the office, notice of the time and place of such lottery. The State Board of Elections shall adopt rules and regulations governing the procedures for the conduct of such lottery. All candidates shall be certified in the order in which their petitions have been filed and in the manner prescribed by Section 10-14 and 10-15 of this Article. Where candidates have filed simultaneously, they shall be certified in the order determined by lot and prior to candidates who filed for the same office or offices at a later time. Certificates of nomination filed within the period prescribed in Section 10-6(2) for candidates nominated by caucus for township or municipal offices shall be subject to the ballot placement lottery for established political parties prescribed in Section 7-60 of this Code.
If multiple sets of nomination papers are filed for a candidate to the same office, the State Board of Elections, appropriate election authority or local election official where the petitions are filed shall within 2 business days notify the candidate of his or her multiple petition filings and that the candidate has 3 business days after receipt of the notice to notify the State Board of Elections, appropriate election authority or local election official that he or she may cancel prior sets of petitions. If the candidate notifies the State Board of Elections, appropriate election authority or local election official, the last set of petitions filed shall be the only petitions to be considered valid by the State Board of Elections, election authority or local election official. If the candidate fails to notify the State Board of Elections, appropriate election authority or local election official then only the first set of petitions filed shall be valid and all subsequent petitions shall be void.
10 ILCS 5/10-6.2