You can look at it like a 2-channel amp. It has 2 + and 2 -.
It bridges itself inside the amp, wich meens i can run 2ohm to each channel! And it will give each "individual" amp 1 ohm.
Thats at least how it works.
So the best is the subs in pairs. And each pair wired at 2 ohm`s each. So the best thing whould be dual 2 ohm right?