title: prevent duplicate links when using wp_insert_link
body: <p>I have a lot of links in my wordpress database. There are so many that sometimes I insert the same link twice. I was wondering if there is a way to fix this by adding some code to a plugin.</p>
  
  <p>Specifically I'm wondering if there is a filter that I can use in wp_insert_link to check if the link I'm about to insert already exists, and if yes - then throw a error.</p>
  
  <p>Possible?</p>