Velodyne Digital Drive Series subwoofer in stereo

Possibly the difference between one or two subs is non-quantifiable. I certainly heard a difference when I added a second Vandersteen 2W sub to my system running in stereo. I believe I hear quite well the stereophonic effect of the low frequencies. The room certainly fills with low sound better than with one sub, and there have been no problems with nulls that I'm aware of. Currently I have ten 8" bass drivers operating and simply the presence of the additional drivers makes exceptionally deep frequencies audible. Previously, when I operated two subs (with six 8"drivers total) an incredibly low bass note was not even audible. With the addition of four more drivers it could be sensed.

Truthseeker, not to argue...but I my understanding is that there is indeed different information that is sent to L/R subs when run in stereo. I may be wrong about that.
I know that my system (using Vandersteen subs) does not simply make a dual mono presentation. They are literally receiving only L/R signals. Are naysayers suggesting that in all recordings there is never low hz information sent to either left or right, but only both chanels? This may be, but I have never heard of it.
I have listened for years with one sub, then added the other. Whatever it does, using stereo subs alters the listening experience, especially since (and I don't care much if it's technically appropriate or not - it sounds great) the subs are directly behind the main planar speakers in the front corners of the room. To me, it's the ultimate way of integrating the subs with the mains.