Originally posted by freeck:

Every time I meet a troll near a cave, the cave is empty. And vise versa - when I find a cave with no troll anywhere near it, the troll is inside.

Yesterday i ran smack into a 1-star troll while running through the back forest. He was standing right at the entrance to what I assumed was his cave. After killing the 1-star troll I went into the cave expecting to find it empty - but it had another troll inside (common one). So there definitely can be two trolls at a troll cave (one in and one out)..