80kg x 50% = 40kg
Good kirk = 40kg + 40kg replicated = 50% replicated. I was talking about adding to each individual transportee (singular) but you are right, technically Kirk was a single transportee split into two so while each person who stepped off the pad was 50% replicated overall there would be 100% replicated material.
We're saying the same thing in different ways though. Let's leave it there and not be too pedantic. The concept of transporters is controversial enough as it is! ;P