And to add to what you guys have said above, I just started Act III, and I found the gloves in the fire set (the prince). I went to try it with the armor and boots (or whatever) also from the fire set (the king and queen), and found that these two items no longer exist in my inventory. From loading save games, it turns out that the unique fire set items turned into other items (the armor turned into bone armor, for instance), during the transition from Act II to Act III. Not a huge loss, and I haven't noticed any other problems, but disturbing nonetheless.
