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

Years ago, many systems had an A B speaker choice. It seems that faded ( no pun) with the times, but not for me. 

I have stayed with two sets of speakers for the fronts and find it  flexible based on recording and music types. Volume levels too.

My system:

• Oppo 105
• Parasound P7 preamp
• 3 Hafler 9500 amps
• JBL 250 Ti
• Tekton Pendragons’
• 2 DD 15 subs

    The secret sauce here is the P7. When switched to the surround mode (actually stereo) it is wired to deliver to the two sets in the front ( JBL and Tektons) . Using the remote - front to back fade, you can send more or less volume to each set of fronts. 

It gives a choice to the amount of influence each set provides, but almost always the setting is close to split for best sound. As you raise volume, or have older rock playing, the JBL’s win out. Bass is tighter with the Pendragons with more live sound.

Sound is much better when speakers are combined usually.

It seems to work for me.

What a stupid idea to use two dissimilar speakers together at the same time! Goodbye coherence!

Siegfried Linkwitz designed the Watson SEL to support the Orion.
I've found that they also work very well with the Pluto and LX Mini. www.linkwitzlab.com 

Everything is dissimilar.  The "unified theory" is still yet to be proven.  MOST speakers (in an enclosure) are assembled from "off-the -shelf' drivers from the few manufacturers who mass produce them.  Who defines (and decides) what is "similar?" Virtually most speakers enclosures with their drivers that are commercially available aren't designed to be assimilated into speaker "X."  I've heard systems far into stratospheric price levels with 2 sets of top-drawer speakers driven reference components (every piece $10,000 and above) that were highly satisfying.  Paul McGowan of PS Audio has more than once lamented about the arrogant, opinionated and narrow-minded rantings of some in our hobby.  You can disagree and still be polite and civil.

Pairs of dissimilar speakers? No. Pairs of matched speakers, sure. Double Advents are well known as are double pairs of KLH-9's. Double Quads are another well regarded option. Ever consider that Acoustat 2+2 are really doubled 1+1? Nobody thought that was odd that I remember.
Personally, I run two pair of VMPS Tower II at the same time and have for years. They're side by side thank you and sound wonderful.
Anytime you see "Purist" in this hobby watch out. That's the snob side of things leaking out over the experimenter side. There's no rule that says that two pairs of speakers, similar or dissimilar will sound one way or another. If you have such and want to play about, keep in mind that you might find something you like for little or no cost.
That's how discoveries are made.