The tall one is Olney and the seated one is Willie. Their information is written on the back of the card as follows:
Olney Lee Rudd b Jan 17, 1874
Carroll Co Ark, near Rudd, Ark
William Mann Rudd Jr b July 12, 1878 Springerville Arizona
Dr William Mann Rudd and Eliza Catherine Mann
I was wondering at Olney’s uncomfortable posture and realized he probably has one of those head holder stands behind him. Upon closer inspection, he appears to be grasping something in each hand, probably hand rests of some type on the stand. Although the photo is not dated, Willie appears to be about 6 years old, putting this sometime in the early 1880s.