I'm wondering if there is some confusion here. I can find a marriage record for Mary Shell, born about 1803, to Jacob Limbaugh, born about 1802, according to the ancestry.com database, "U.S. and International Marriage Records, 1560-1900." This information exactly matches what is listed for Mary Limbaugh in the 1850 census (Jacob is shown as the last name in the family, below the children, and his information matches, as well).
I also find a marriage record for George F. Limbaugh, born about 1797, and Katherine Edinger, on 6 May 1830. This record is from the same source. Both couples married in Cape Girardeau County. George is shown with an estimated birth year of 1800 in the 1850 census, and he is married to Catherine. So Ron, is it possible that you have mixed up which wife married which cousin? Do you have any sources to verify your information?
Teva