Does anyone play two pairs of speakers at the same time?

We did that in college. Nothing like two pairs of JBL driven by 60 watts of Kenwood and Pioneer (using only the highest quality lamp cord, it should go without saying) in a 8x15 foot dorm room. Totally recreates with perfect fidelity the experience of high sound pressure levels.

Has anyone seen the Tekton "The perfect Set"? It has a few tweeters in each cabinet!

But if you read the white paper on the design behind this, it is not just sticking a few tweeters in the cabinet.

They are all acting as one driver. In other words, lobing, phase, cancellation, etc, are all taken into consideration by Eric Alexander in the placement and crossover design.

He has several very informative vids on YT explaining the reason for the design. And again, it is not just sticking a bunch of tweeters in a cabinet. 

I will reiterate what I said months ago, the chances of getting a good, flat frequency response, with phase not becoming any worse than one pair of the speakers being used, with no weird new, cancelations, standing waves, increased dips or bumps in the frequency response, or other unpredictable results, are not good. 

If one likes the result, that is fine.  Maybe you like whatever frequency aberrations are caused by multiple drivers operating at the same frequencies. 

I agree that if you have one monster set of speakers with some serious drivers (Cornwalls?) that stacking 2 sets might be superfluous.. bit i am in the camp of having the extra small speakers lying about not earning me a dime... and they do bring a bit more rawk to me rawknroll ... tallyho!!

playing two pair of speakers at the same time cannot offer hi fidelity unless it uses two identical pairs and placed on top of each other

I am running ELAC Navis book shelf  active speakers currently.

I have acquired another identical pair of the ELAC's  and am considering a dual pair configuration as being discussed in this forum.

Worth pursing?