For in-text citations (Per the MLA Handbook (8th edition), p. 55: Including only the author name and page number in a parenthetical citation is insufficient if more than one work appears under that author's name in the work cited list. In that case, include a shortened version of the source's title.
In the Works Cited (Per the MLA Handbook (8th edition), p. 113: To cite two or more works by the same author, give the name in the first entry only. Thereafter, in place of the name, type three hyphens, followed by a period and the title. The three hyphens stand for exactly the same name as in the preceding entry. This sort of label does not affect the order in which the entries appear; works listed under the same name are alphabetized by title.
(Haynes, Noah's Curse 84)
(Haynes, The Last Segregated Hour 57)
Works cited (don't forget to indent the second and subsequent lines):
Haynes, Stephen R. Noah's Curse: The Biblical Justification of American Slavery. Oxford University Press, 2007.
---. The Last Segregated Hour: The Memphis Kneel-Ins and the Campaign for Southern Church Desegregation. Oxford University Press, 2012.
MLA Handbook. The Modern Language Association of America, 2016.