Quote Originally Posted by Peregrine View Post
it has been posted by Blizz that Hunter's mark actually stack (different ranks)
That's not the bug.

The bug is that because of spell batching, you can put 5, maybe 6 MAX rank hunters marks on a single target. By having different levels in the hunters mark talent 1-5/5, you can stack those.

If you do it sequentially, they don't stack. If you do it all at once, they stack.

(Edit, I assume this bug is because of spell batching).