Excellent thread. I just tied a few sculpins with two hooks for the first time. The reason was because I was fishing at night and had been missing fish recently on streamers due to short strikes. The two hooks worked pretty well - I only lost one fish, on a very violent strike. I was pretty disappointed, though, that every fish I caught was hooked on at least the front hook, and the ensuing damage was, in my opinion, excessive. I also foul-hooked more fish than usual, even for night fishing. I think I'm going to do what Davez suggests and just use a stinger hook with nothing else, effectively a jointed streamer with one free-swinging hook. I can't see any other logical solution.
By the way, if you're as cheap as I am and hate the idea of using two hooks for one fly (and even worse - cutting the hookpoint off one of them), just buy some longshank hooks and cut them in half before tying. By the way, using longshank hooks as is causes a lot of lost fish because they can get so much leverage against the shank and throw the hook so much more easily.
Also, ditto the barbless comments. Not only is it much better on the fish but also on you if you're fishing a fly with multiple hooks. The same is true when fishing a multiple-fly rig. Getting a hook stuck in you while you're trying to unhook a fish can be painful. I remember a few years back watching with wonder as my brother, while unhooking a large fish, dove headfirst into the river and started thrashing all around. Afterward, he explained as I laughed at him that the fish had wriggled free before he had unhooked it, and as it made a run for it it drove my brother's trailing fly deep into the webbing of his hand. To keep from snapping off his flies or tearing up his hand, he had dove into the river after the fish. All ended well, as he tackled the fish again and unhooked both it and his hand, but he's been more careful unhooking fish since then.
And you only need to get a hook buried in you past the barb once before you go barbless. Or, for those with a truly extraordinary intellect, you could be smart enough to go barbless before that happens.
-Shawn