A single person cannot have two separate and distinct wills at the same time on the exact same subject. Separate and simultaneous wills imply separate and simultaneous persons. Persons do not need to have bodies. God the Father possesses personhood without a body, as do the angels. He was praying to the Father about the ordeal He was about to undergo.
Several points are worth bringing out here.
First, in this passage, Jesus addresses the Father. The cup Jesus is speaking of is the immanent ordeal of betrayal, scourging, and crucifixion. Jesus did not want to go through this. He was expressing His desire. It was His will not to undergo the severe ordeal ahead of Him.