As with eels, I had a bluefish chop up a sluggo up to the point of just exposing the imbedded portion of the single hook.
This was repeated some time later in a different area just as the sluggo hit the water. I didn't even have time to reel.
You can feel them chomping up the length of the sluggo to within a hairs width of the hook, in the dark.
Had I had a tandem hook set-up, I imagine they probably would have stopped just short of the trailing hook.