I don't know, but I have a guess. Investors model VC returns very carefully and use them in their portfolio to achieve a certain kind of risk profile. That mo

I don't know, but I have a guess. Investors model VC returns very carefully and use them in their portfolio to achieve a certain kind of risk profile. That model is based on each dollar being invested once. If it's invested more than once, the model gets exceptionally complicated. But like I say in the article - I'm not an expert in this stuff; I'm just a well motivated student. I hope someone from a firm will weigh in with a more definitive answer.