Should I add second sub that is same brand I have now or try to get better?

[STARSCREAM]

I currently have a BIC Acoustech H-100 subwoofer, since moving my theater stuff to the living room it is such a bigger space that my sub just can't fill it good. Sorta sounds like it only hits one side of the room really good. Just to test out 2 subs I added in an Onkyo HTIB sub to try out and it really evened out the sound. It seemed to make most bass alot better but also seemed to maybe make the lower end stuff like the infamous Kung Fu Panda Skadoosh not as good.

My question is that I'm thinking of buying another BIC Acoustech H-100 so I'd have dual H-100's that match or should I maybe try to just sell the one H-100 I have now and then put all the money towards a higher end sub??? I'd only have one sub then though and am not sure if it would be enough.