I find only one A. Thomas in the 4th.

George Martin

Albert C. Thomas

Residence was not listed;
Enlisted on 9/11/1861 at Camp Burnett, TN as a Private.
On 9/11/1861 he mustered into "G" Co. KY 4th Infantry
(date and method of discharge not given)
Promotions:
* Sergt 9/11/1864

Also in Co. G is:

William Thomas

Residence was not listed;
Enlisted on 9/14/1861 at Camp Burnett, TN as a Private.
On 9/14/1861 he mustered into "G" Co. KY 4th Infantry
(date and method of discharge not given)

Additionally, three other Thomas' served in the regiment, John J. in Co. I, William in Co. D, and William H. in Co. H.