Should multiple mid-range drivers in a single tower be identical? What about the drivers used in two towers?
Since bass is pretty much non directional feeding them both the same mono signal might be best.
Some speaker manufacturers go to great lengths to match drivers and many hand select crossover components.
Personally, I would use identical subs. But if the added sub is similar, such as size of the driver and cabinet type, and you're crossing over no higher than 80hz, I'm sure the earth will remain intact and the sun rises tomorrow morning.
It depends on one's level of OCD.
Only up to 80Hz in order to minimize localization? Why would localization be a problem with duals? Wouldn't they simply (or complexly) image higher freqs? And what's the matter with imaging?
I would assume if they were crossed high, and each had a distinct sound, it might be somewhat annoying.
My opinion on the L+R in mono is no. There is music that have one channel bass lines. Example here between 1.50 and 2.05.
That's exactly why I use identical dual subs running in stereo.
That's exactly why I use identical dual subs running in stereo.