You are just wrong here..both are about the same if you average out dmg and rpm, but it's more of the enviroment you're playing in (ex. MG36 has a higher rate of fire, so that would be better for CQC, PKM has higher dmg and more accuracy, so it is preferred for wide open spaces)
MG36 has a better min deviation and recoil pershot. That and the sight picture alone makes it far superior to the pkm.
Even in situations that the pkm might be SLIGHTLY more accurate, the mg36 is putting 3 rounds down range in the time it takes the pkm to fire 2, and that means you have a 30% chance of hitting.
And lets be real here. Firing at a target of greater tha a 100 yards, your just gambling that three bullets are going to hit out of the 40 you will need to fire before he manages to kill you with a rifle.