This plugin enables you to have 2 titles for 1 post : one will be displayed on the post page, while the other one will be used on the homepage, the categories, tags and archives. This helps improve your internal linking, as you can see it on many news websites over the interwebs.
You'll just see a second title input just above the text input in the admin, which stays optionnal : if you don't set a second title, only one will be used.
For further information, please visit
this link.