Ken,
That is correct. That roster is frought with errors.
One thing bothers me though with that headstone. Why would they put "Bryant"(Post war records more often than not spell it "Bryant") on the headstone when McGarrah only served in that Battn. 8 months and then served 2 1/2 years under Adair? I did make a mistake when I indicated he enlisted for 3 years. It was actually for 1 year which may be the answer to this riddle. Being from Ark., he could have gone home after his enlistment period and later in the war re-enlisted with Bryan again in his SS or 3rd Cherokee regiment. I have found a few guys from Benton and Washington Counties that did just that.
Hope you are doing well.
Hugh