Hmm if you are talking about doors there is one on each side for 2 knobs. However, when it comes to 4 knobs that means that you have a double lock, 2 on each side to prevent thieves breaking into your home.
On another note if you are referring to 2 KNOTS and 4 KNOTS. It is a stringing pattern, which I believe that there is tons of info in this forum. Please use the search function on the top right corner of the forum.