Dipole speakers in a 7.1 setup?


I have a mixed and matched M&K 7.1 speaker system consisting of 4 S85's, one S85-C center, one pair of 500THX dipole surrounds, and v-75MKII subwoofer. My question is, in a 7.1 setup, would it be better to use the one pair of dipole surrounds I have for the rear side speakers, or the rear back speakers? Thanks very much!
Convert?fit=crop&h=128&policy=eyjlehbpcnkioje1mda5nzk2mzesimnhbgwiolsicmvhzcisimnvbnzlcnqixx0%3d&rotate=exif&signature=96f5258c2ef12b1f9860a7544501c2e1ca7aa1b5c98988c9a4ab43d988e69b5f&w=128sblagg