I am a great grandson of James Sanders. It is possible that Milford served in both units, the 15th Mo and Colorado Cav. The Union Army had an amnesty program that allowed Confederate prisoners to take an oath and enlist in Union Army units in the West. These soldiers were called galvanized Yankees. The intent was to send them West to fight against the Indians. Regarding his alledged death in Oklahoma, James is also rumored to have died 1906 in Oklahoma. Maybe both were there or family lore has mixed these brothers up over time.