Having 2 subwoofers in a small room is a waste. Only if you have a very large room would you need 2.
Low frequency harmonics travel a long way and it is the placement of the woofer that is the most important thing to consider. The corner of a room is the best, with the subwoofer placed so that it angles against the corner facing out towards the room. Make sure there are no items in front or near the subs that will soak up the sound waves.
If you do use 2 sub's, then you do not want them pointing at each other, since the sound waves would cancel each other out and create standing sound waves. And 1 of the subs should be set at 80hz and the other at 180hz, that way you get the best low frequency across the band with out making either sub work very hard.
If you are going to use 2 woofers connected to a computer, make sure both of them are powered sub's. Meaning that they have their own amplifiers built in. So you will have to make sure there is a power plug near by.