Mo. Rev. Stat. § 115.351
No person who files as a party candidate for nomination or election to an office shall, without withdrawing, file as another party's candidate or an independent candidate for nomination or election to the office for the same term. No person who files as an independent candidate for election to an office shall, without withdrawing, file as a party candidate for nomination or election to the office for the same term. No person shall file for one office and, without withdrawing, file for another office to be filled at the same election. Receipt by the secretary of state of proper certification of nomination pursuant to subsection 1 of section 115.399 constitutes withdrawal by operation of law pursuant to subsection 1 of section 115.359 of any presidential or vice presidential nominee from any other office for which such nominee is a candidate at the same election. Any person violating any provision of this section shall be disqualified from running for nomination or election to any office at the primary and general election next succeeding the violation.
§ 115.351, RSMo