Replicate the portfolio aggregate function for simulations.

I love the Aggregate feature, since it allows a person to see which holdings occur in more than one portfolio. It would also be great in simulations, to establish if 2 simulations hold different stocks. As I develop more than one portfolio, I want to make sure that they hold differing stocks.

Ideally, it would look at the same time "slice" of each simulation, but just comparing current holdings would be a GREAT addition.