I've been told, "No" that the only real test is for the exact subwoofer (or at a minimum the same make/model) for the test. Each sub will act differently in your room based off of woofer size, cabinet dimensions, amp, tuning, etc...
As for how to find the best location for a 2 sub setup, I don't know exactly. Again, you should use the actual sub(s) that you are going to have, and go from there. I am sure that someone who has done it will chime in. I am curious too since I will eventually have 2 subs in my theater as well.
