This paper derives the kinematically identical manipulators (KIMs) of the 2-RPU + UPR parallel manipulators (PMs) and performs a comparison study among them. Based on the principle for deriving KIMs, ten non-overconstrained and 12 overconstrained KIMs of the 2-RPU + UPR PMs are derived. The 2-RPU + UPR PM and its KIMs has identical kinematics but different constraints. On the basis of motion/force transmission indices, the optimal design of the 2-RPU + UPR PM and its KIMs is carried out and the optimal parameters are obtained. With the optimal parameters and the definition of constraint performance, their constraint performances are compared. The comparison study with the 2-RPU + UPR PM and its KIMs is helpful for obtaining the optimal architectures among them.