From the following census data it appears that there are 2 different Maxmillian Trahan's married 2 different Marie Landry's or he married 2 women and ran between parishes an awful lot.
Source: "Louisiana Marriages, 1816-1906", database, FamilySearch (
https://familysearch.org/ark:/61903/1:1:F4ZS-1YY : 14 January 2020), Marie Zeonide Landry in entry for Maximilien Trahan, 1837.
Louisiana Marriages
: Maximilien Trahan
: Marriage 9 Sep 1837 Louisiana, United States
: Spouse Marie Zeonide Landry
Source: "United States Census, 1850," database with images, FamilySearch (
https://familysearch.org/ark:/61903/1:1:MCJ4-8QV : 4 April 2020), Maxmilien Trahan, Lafayette parish, Lafayette, Louisiana, United States; citing family 176, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).
United States Census, 1850 Lafayette parish, Lafayette, Louisiana
: Maxmilien Trahan Male 34 Louisiana
: M Z Landry Female 28 Louisiana
: M M Trahan Female 12 Louisiana
: M D Trahan Female 10 Louisiana
: M Trahan Male 9 Louisiana
: Pierre Trahan Male 7 Louisiana
: Beloyne Trahan Male 6 Louisiana
Source: "United States Census, 1850," database with images, FamilySearch (
https://familysearch.org/ark:/61903/1:1:MCJX-8KW : 4 April 2020), Maximilien Trahan, Vermilion parish, Vermilion, Louisiana, United States; citing family 33, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).
United States Census, 1850 Vermilion parish, Vermilion, Louisiana
: Maximilien Trahan Male 34 Louisiana
: Marie Landry Female 30 Louisiana
: Emile Trahan Male 13 Louisiana
: Clairville Trahan Male 11 Louisiana
: Emilia Trahan Female 8 Louisiana
: Jules Trahan Male 6 Louisiana
: Emelie Trahan Female 5 Louisiana
: Carmilien Trahan Male 2 Louisiana
: Felicia Trahan Female 0 Louisiana
See the births of children here: different mothers matching children in census data.
https://www.familysearch.org/search/record/results?q.givenName=Maxmilliam&q.surname=Trahan&q.birthLikePlace=LA&q.birthLikeDate.from=1813&q.birthLikeDate.to=1817&q.spouseGivenName=marie&count=20&offset=0&m.defaultFacets=on&m.queryRequireDefault=on&m.facetNestCollectionInCategory=on