No, as lorna said keep them separate. Id just do the different salt in the water change, no half and half, should be fine. Eventually with enough water changes itll be completely switched over.
Ive used deep ocean on my reef tank for the simple fact its dirt cheap and good enough (salt is salt, unless you have alot of Ca, etc sucking corals)... but will probably switch to Marin because its an awesome salt. Either one of your choices would be totally fine for you, really.