65 ILCS 5/2-1-7
Before action is had upon any petition for incorporation of a city or village, the name proposed to be given to such municipality shall be filed with the Secretary of State. If it appears from information in his office that the proposed name has not been adopted by any municipality, the Secretary of State shall grant a certificate so stating. If the proposed name is the same as the name of another municipality in Illinois, the Secretary of State shall inform the petitioners thereof. Thereupon, the petitioners may file another proposed name with the Secretary of State and they may proceed in the manner set forth in this section. No action shall be taken on the petition for incorporation until the Secretary of State has issued such certificate.
65 ILCS 5/2-1-7