Using 2 Subwoofers

My room is very similar in size to yours, and I find my single Velodyne F1500R is more than enough bass. Location is on one side, in the center it did not produce much bass. My main speakers are ADS 1590/2's, full range in their own right. But still the sub is needed. I can't imagine sticking 2 subs in a room my size!

Multiple subs, placed asymmetrically should even out some nodes....bumps and dips.
Equalization will help for a small area at the expense of larger peaks or dips elsewhere. For a single listener, a single equalized sub should work. In my room, where I have the TV, I got lucky and have a wacky, 8 sided room with an off-center vaulted ceiling. I've looked (listened, actually) for bass bloom and suckout without much luck. I also crossover below 40hz and run my panels full range.....That, too, may help.

One of the advantages of using 2 subs is you can get away with smaller drivers.
A room that sounds good with a big 12, or 15" sounds even better with 2-10" subs.
You pick up alittle speed, and your room does not have to compensate for such nodes (trying to support 30hz clean).
A stereo 50hz, sounds alot cleaner than a mono 30.
I once had 2 Klipsch 8" powered subs hooked up, and they sounded better than all the premium single (12&15") subs I have owned, especially on 2ch music.
Just my opinion, I am no expert by anymeans.

I agree with Bob. To restate and expand on his point.

If you have Audyssey or similar digital room correction (DRC) in your HT electronics, a single well chosen sub (SVS and JL are highly regarded for dual music and HT use) should be more than enough for your space. The DRC will correct for destructive room effects, so you needn't worry about addressing that issue via strategic placement of multiple subs.

The ability to address room issues via strategic placement is the primary reason I'd choose multiple subs. In this respect, DRC or multi subs are an either/or solution to the same problem. You can use both (I actually do so, but for quirky system and room specific reasons), but you usually needn't do both for smooth FR in the deep bass.

While it's also true that multiple subs will - all else being equal - provide higher output for any given distortion level, in your smallish space a single high quality subwoofer should not be remotely stressed into audible misbehavior.

Marty