Belinda,
Both men were from Clarke County, MS and both enlisted in Quitman, so that complicates the matter. The David M Carr you inquired about (Co. D, 7th MS. Btn.) appears on the 1850 census as the son of John P and Maranda Carr. After the war, he moved to Texas, where, after his death, his wife applied for a pension for indigent widows of Confederate veterans. She signed (with and X) as Mrs. A. M. Carr and stated that she and her husband were married in Choctaw County AL on 12 Nov. 1882. Here is a link to his grave with a photo of his marker: http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=15871971 If this listing is correct, his middle name was Milton. The other man's middle name is listed on family trees as Marshall.