Automatic undue redirect

A user create a post with the same title as an older post: 'Inspirational Quote: Completion'

When the new post was published (see ), if a user clicks on the link (or image or 'more' link) s/he is redirected to instead of which is the URL of the new post.
I tried to change the title of the older post as well as the URL but it did not change a thing. I also disabled WP Super Cache and deleted all cache as well as in browser but to no avail!

Right now the URL of the older post is not but !

Can you help please?