It's a matter of IV and EV. If you clone the Rhyhorn into 2 copies,
The first evolves @ level 42 (habitual way) and become Rhydon, not Rhyperior.
The second evolves later on @ let's say level 70. Rhyhorn may have learn every move it can learn before evolving. You give them Rare Candies until level 100. If since level 1 both of them had candies, then their stats should be equal and the same. If one defeated Patrats, it will have a higher attack.
Rhyhorn evolves into Rhydon @ level 42, then evolves into Rhyperior when traded with a Protector item. No matter how many level it gained.
Hope I helped !