To remove the duplicate title tags you need to install an SEO plugin either Yoast or RankMath, both these plugins offer you to remove the duplicate title tags and allow your pages to appear different in eyes of Google so that they can be indexed properly.

As shown in the above code, Go to Titles and Meta Tag on the Rank Math plugin page from your WordPress dashboard and then make sure that at least you have %title% mentioned in the single post title.

This will ensure that whatever is your main post title that should be your title tags. And this will remove any duplicate title tags if present across your website.

Also, you need to make sure that your RankMath plugin settings are as per the recommendation given by RankMath itself. Follow their website to make sure you have all the settings completed properly and saved.

Upon fixing the RankMath setting you should not face any duplicate title tags message on your search console either on Google or Bing.

If you are facing duplicate title tags for your homepage then you need to make sure that the homepage has %page% present in the homepage title of the RankMath plugin.

If you are using a static homepage then this option will be disabled for you and you need to edit the required homepage and add the title and meta tags as per your requirement to the RankMath plugin tool that is displayed on the right side of the block editor.