If I am citing two poems, each by a different poet, should I use the word line or lines the first time I quote from each poet’s work?
Yes. The MLA Handbook says that “in your first citation” of a poem, “use the word line or lines and then, having established that the numbers designate lines, give the numbers alone” (121). This guideline applies not only to poems by the same author but also to poems by different authors. Its purpose is to distinguish line numbers from page numbers in your in-text citations. You should place the word line or lines before the line numbers in your in-text citation the first time you quote from any poem, even if you have previously cited a poem by the same author. After the first citation of a poem, you can omit the word line or lines.
MLA Handbook. 8th ed., Modern Language Association of America, 2016.