After looking at the first two, it appears that one reference in each file refers to the officer as Bvt. 2nd Lieut. I'm guessing that the State of Tennessee didn't use this rank in militia service, but Hardee's Tactics does reference this rank, a manual commonly used by Confederate officers. Someone familiar with 'old army' useage or specifics from Hardee's Tactics must have completed the two rolls which include this term.