I normally snell both hooks(if circle hooks). I never fish a loose sliding hook.
But I have found a smaller circle on its own that is snelled and baited correctly is very effective and the use for 2 circles then is pointless... If I bait up a head section of bait I make a hole through the jaw(above and through both lips)and put a cable tie through it and I don't pull it too tight so the head can still swing on the cable tie. So I leave a loop... Second cable tie through the first one and around the bottom of the circle hook and that one I pull tight.
Has never failed me!!! Only if I target big rays I will use 2 circles on a whole occy bait.