CMS automatically duplicates linking to related posts

Issue raised by Sarah:
"If I link article A to article B the system automatically links B back to A as well.
So any post that I linked to 'Your New Baby' will then also have a link from 'Your New Baby' to it. This is not ideal as I linked many posts to this particular post (for example) but don't want to link from this post to all those articles. "

This was originally filed under https://github.com/praekelt/unicore-cms/issues/42