Many people shared the same first and last names, so a name match in a unit from your target state may frequently be wrong. It's even possible to find two men about the same age who live in the same county who share the same name. Since men from the same community frequently served together in the same companies, you will need to know where the man in question lived in 1860. The Federal census for 1860 should give you county residence and age, and that's valuable information.
In most cases a Confederate soldier joined a company being recruited near his home. There are exceptions, of course. For instance, someone who had recently moved away might elect to return home to enlist with old friends and family. Another might choose to enroll with cousins or friends who happened to live in another county. Intrigued by the 'fun' and adventure of a military camp near his home, a young teen from Alabama might even join a Texas cavalry unit!
People who aren't familar with military records are frequently misled by simple name matches. For instance, during an idle moment yesterday I happened to read a published family memoir about a veteran named Calvin Guthrie from Winston County, Ala. Calvin was supposed to have been a Cherokee Indian, so the writer immediately found him in the 2nd Cherokee Mounted Rifles. Isn't the NPS index great? The NPS index also referenced Calvin as a member of Co. "I", 1st Alabama Cavalry. Both units fought under the Confederate flag, or so the writer imagined.
Problem #1) The 2nd Cherokee Mounted Rifles was recruited in the Indian Territory, not north Alabama. The regiment served west of the Mississippi, hundreds of miles from Winston County.
Problem #2) Service records of the two units are concurrent, meaning that Calvin Guthrie would have to be in two places at the same time. The family memoir tried to resolve the problem by assuming that he transferred from the Alabama unit to the 2nd Cherokee Mounted Rifles. Never mind that he died as a member of the 1st Alabama Cavalry after transfer to the 2nd CMR!
Problem #3) The 1st Alabama Cavalry served under the Stars and Stripes, not the Stars and Bars. The writer simply overlooked that bit of information. If Calvin only knew that his descendants thought he was a Confederate soldier!
This would be amusing if it wasn't published in a family reference source for Winston County. It's a sad example of mistakes that can be made by relying on simple name matches in the NPS index.
Look carefully at similar spellings of the name in question. Remember that many men could not write, and clerks often recorded names the way they sounded. A last name like Burrows could be rendered Burris, Berris, Burroughs &c. A long first name like Jeremiah or Leonidas was easier to record unsing the first initial only. Later, during record transcription, a middle initial of M. might be misread as a ‘W’ or a ‘N’, a cursive 'L' might be mistaken for an 'S', a cursive 'A' might look like a 'C' &c. You have to be imaginative in your pursuit of an elusive ancestor.