Hi Norm,
Having 2 subs, assymetrically placed in the room is the best solution since it allows one to fill in the holes left by the other.
Having them placed in almost the same location deprives you of this benefit.
Having said that, having a single sub, properly callibrated and integrated with the room and speakers (that's 2 different operations) is probably going to be great. Try it.
Best,
Erik