no need to with copper treatment, though it is possible to do both at the same time, i would maintain a lower salinity, perhaps 1.022 as lower salinity requires less work for the fish to maintain homeostasis, aka, less stressful environment and therefore a better place to acclimate and heal. I do not know of many people who do both, its normally either hypo (1.010 salinity) or copper never really both.
However, if you do maintain a lower salinity it will take a lot longer to acclimate to a dt with a salinity of 1.026 as sudden increases of salinity (were talking hours) can be severe enough to kill the fish.