2 subwoofers?

I have #2 B+W 802 speakers powered by a Classe 5 channel amp. 250 Watts per channel. Each speaker is getting 500 watts. One channel powers the woofers and another channel powers the mid and tweeter.Plenty of power. I have one Velodyne 1500 SPL sub under the left speaker. I am considering getting another one for the right speaker.People are telling me that one sub is enough and that getting another one would only be a waste of my money.The Velodyne 1500 is a powerful sub but I can't help but think getting another to match the left side would improve the sound. Any input will be appreciated.
Even Fathoms or Gothams that have plenty of power for a certain room will greatly benefit from a second, with better bass loading, but, also, and more important to me, is much better imaging without shift. It's just wrong what is said about not being able to locate LF sound sources. Even with a steep cutoff at 35 hertz I can easily locate a single sub playing in my room. My 6 year old said "what is that box making noise" when he heard the system with a sub. I asked "what noise" and he said "brrrmm brrrmm". Two of them close to the speakers is the ticket.
I agreed with Kiddman and others, 2 is better than one, from my observations in my system I was always able to locate the single sub when I had one no matter where I placed it. Then I bought another and put them close to mains and bass is smoother and very hard to pinpoint the bass location.
Thanks for all of this valuable information everybody. I have decided to get another subwoofer. Now I have a new problem. For the life of me I cannot locate another subwoofer to match the one I currently have. Velodyne stopped making the 1500r spl years ago and I cannot locate one through this site, eBay, craigslist or any where else. Can I set up a similar in specs but different model, or must they match for sonic reasons? I have given myself a headache!
Sell yours and get two DD12 or15 instead. These were the best velodynes made.