As could do to avoid duplicate content in the title. For example if a user makes a post go to United States appear in the title of the post go to United States.
Suppose someone else comes and puts the same title go to United States could establish how do not allow the user to publish this post? Telling you that the title of the post go to United States already exists, you can not publish and must choose another title.
Thanks

There is no such feature by default in miniBB. The add-on might be needed, which checks all topics titles, before the new topic is being posted. It's custom add-on.

I personally think this feature is a waste of time. You can't force all users be smart and intelligent. Moderation exists for such purpose.
Additionally, in miniBB there can't be similar titles even if you use some of the mod_rewrite-related URL add-ons, because each topic has its unique ID visible in the URL.