A search of the Headstones Provided for Deceased Union Civil War Veterans, 1879-1903 turned up two cards for headstones provided apparently for the same man. The cards have to be referring to the same man as there can’t be two Alfred Butlers in Co. K of the 9th Michigan Calvary. While it is possible that there is, the chance is fairly slim.
At this writing I’m not certain what is up with the two stones. It’s possible his body was moved. It’s possible the units for these two man are not both correct.
I think this Alfred Butler is the same one who is the son of Benjamin Butler in an 1850 Census enumeration in St. Clair County, Michigan.