Bob, George G. Dunn served in both the 26th Arkansas (Confederate) and the 2nd Arkansas (Union). According to the muster-in roll of Co. A, 2nd Arkansas Infantry, U.S. Volunteers, he was age 31 when he enlisted on September 1, 1863; born in Rutherford County, Tennessee.

He had previously enlisted in Co. H, 26th Arkansas Infantry, at Clarksville, Arkansas, on June 13, 1862; and was mustered into Confederate service at Fort Hindman, DeValls Bluff, Arkansas, on July 1, 1862, for three years or the war. He was present for duty on the June 30, 1863, muster roll, then was reported absent without leave on the February 29, 1864, roll.

The George Dunn who mustered with Co. B, 10th Arkansas Militia, at Clarksville, Arkansas, during the period February 22 to March 19, 1862, was, as far as I can determine, the same man.

His widow applied for a U.S. pension in 1889, which corresponds to the year of death of George Granville Dunn.

I'd say you nailed it.