In looking at several trees on sites outside of Ancestry.com, it would appear that two sisters have been combined. There is Martha/Margaret and there is Caroline....both of them have a tendency to carry both names.
Here is Marg C that married Swen Brown in 1841
"North Carolina, County Marriages, 1762-1979 ," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:VXTD-ZQQ : 4 November 2017), Swan Graham and Marg C Trammel, 07 Apr 1841; citing Macon, North Carolina, United States, p. , Office of Archives and History, Division of Archives and Records. State Archive of North Carolina and various county Register of Deeds; FHL microfilm 19,268. and "North Carolina Marriages, 1759-1979," database, FamilySearch(https://familysearch.org/ark:/61903/1:1:F8YK-DPY : 10 February 2018), Seven Graham and Marg C. Trammell, 07 Apr 1841; citing Macon,North Carolina, reference ; FHL microfilm 6,330,299.
Then Caroline Trammel is listed as the wife of Levi Brown in her daughter's death record "North Carolina Deaths, 1906-1930," database with images, FamilySearch(https://familysearch.org/ark:/61903/1:1:F3DW-JRH : 17 July 2017), Caroline Tramel in entry for Josaphene Brown, 13 Jan 1919; citing Cowarts, Caney Fork, Jackson, North Carolina, reference certificate # 319, State Department of Archives and History, Raleigh; FHL microfilm 1,892,461. And Caroline living with her parents "United States Census, 1850," database with images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M4B8-SYD : 12 April 2016), Caroline Trammell in household of Jacob B Trammell, Macon county, Macon, North Carolina, United States; citing family 359, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).