Why you want two or more set of speakers????
I have two pairs of front speakers (2L + 2R)
... I got opinions that I might have problems, but I didn't listen
and set up the two pairs ....
I did it, not because I was lacking sound, the speakers sounded good to me (but, I need to use REW to know for sure how my system is performing) ...
I did it, because I removed a pair of speakers that I was using as surround, and instead of putting them away I decided to add that pair in the front .. now I'm using them with the speaker selector A + B in my receiver.
I gained 5bds using the four speakers instead of two ... but after I use REW, I will decide to keep it or remove it ...
Here is a picture of what I have (you can see that my speakers are small, that help with position)