I think what people are trying to find out is are the subs single voice coil (SVC) or duel voice coil (DVC).

If they are duel 4 ohm voice coils then you'll need to run at either a 1 ohm (all four coils in parallel) or 4 ohm load (each one of the subs 2 coils in parallel with the two subs in series). Correct me if I'm wrong.

If both single 4 ohm voice coils then you'll want to run them at 2 ohms. There are lots of web sites that will explain how this works, I cant think of any at the moment.

You should decide on a configuration because many amps will have different power ratings at different resistance loads, generally the lower the resistance the higher the power rating.