Eh hem!...Subwoofers... What do ya know?

Reason i ask is i have 2 x18” jbl 2245 aiming at about 20” apart and hung from the underside of floor . And they sound incredible . Not  boomy sound but accurate and on cue. They have a very black background. And only reveal themselves when there is very low program material. 

If you time align the back sub to fire when the front wave hits him and you also phase it 180 degrees, theoretically both waves cancel each other and you don't hear the reflections again

This is theoretically of course in the real world it won't happen unless the room have nothing in it, it is a geometric cube (or sphere) reflective materials all the same etc

I'm sorry I am assuming front and back subs, if you have them on the sides the effect kind of would be the same

And these are not my ideas or research, you can ask Duke LeJeune with Audiokinesis from which I learned everything I know about subs and which swarm array (trolls like the word or not) is the best bass solution I found after trying the conventional ones, he is IMO the one source of truth to go for these matters, I think he have commented in this thread already