Post titles and urls are important for the SEO of your site and having duplicates can have a negative effect. We have helped many users and will tell you how we would prevent duplicate post titles.

Text version of this tutorial:
http://www.wpbeginner.com/plugins/how-to-prevent-duplicate-post-titles-in-wordpress/

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Summary of this tutorial:

Start by going under Plugins, Add New and add the Unique Title Checker plugin:

https://wordpress.org/plugins/unique-title-checker/

There are no settings to configure in this and it will prevent duplicate titles out of the box.

When you add a new post that has the same name as another on your site a warning will pop up saying that another post has the same title.

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