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

Stacked Quads were/are(?) popular. And multi sub woofers are used. But outside of surround sound and home theatre, I don't personally know of anyone mixing different speakers simultaneously .

only while taking hallucinogens 

I have a two channel preamp and run one channel through a McIntosh MC302 amp and the other channel through a Bryston 4Bsst2 amp. One amp is connected to a pair of Pardigm signature S8V3 speakers and the other through vintage JBL L150 speakers. I have the right channel/left channel speakers pretty close together and spacing between the pairs of about 6 feet. This is an odd setup, mating more efficient modern Paradigm speakers with vintage less efficient JBL's so I adjusted the gain on the Bryston amp to match it better. I do like the sound of this setup, but sometimes go with individual pairs depending on the constellations or horoscope or something like that...

Not exactly the same thing but my AV receiver has a mode I think called "5 way stereo" or something like that.  Essentially, you tell it how many speakers you have and it spreads the stereo image among all of them.

I have some very nice L/C/R speakers  - Hales T1 monitors and a big Hales Transcendence Center channel.  I'd spread the stereo image among the L/C/R and it was super enjoyable.  Mostly it seemed to had a big thickening "heft" to the stereo sound, it just all sounded more solid, weighty and substantial. 

Been following but never joined in, until now. I run a pair of Klipsch Khorns, a pair of LsScalla's and a pair of Heresys (mounted up high) in the corners of the listening room.I use 3 Mcintosh MC252 amps and 2 Mcintosh C52 preamps to control everything. It is set up as a 2 channel system and sounds amazing. The standard 2 channel 2 speaker system was always my go too, but when you have Klipsch  speakers everywhere, you kinda want to use them. It is absolutely worth trying the multi speaker layout. Have fun with it and forget about the labels.