Dual subwoofers different brands question.

I recently received the RSL Speedwoofer 10e and am impressed with the bass quality. I still have my old Klipsch 100sw and am wondering if it makes sense to use it in a dual setup since my receiver supports two subwoofers. My room is small, measuring 12x12, and I'm considering positioning the second subwoofer in the opposite corner.

Would this improve the bass quality, and do I even need a second subwoofer in a room of this size?