Hello- How to analyses duplicate Content issues in website?

Duplicate content is a copied content which is already published on another website or blog. These contents can be checked using various online tools like Copyscape. These contents are harmful for your website and should be removed immediately to avoid search engine penalties.

Copy escape online tool will helps you to find your duplicate content

Nowadays Google is more focused on the quality content present in the website. You must know that the search engines will NOT crawl your pages with duplicate content you have to make it unique and plagiarism free. Duplicate content can affect your rankings badly. Here are some ways that can help you out:-
Google Duplicate Content Checker- just copy the phrase of your blog post content & search as it is on the Google in double ("") inverted commas

You can go to Google Search Console (Google Webmaster Tools) > Search Appearance > HTML Improvements, and see if there's any "Duplicate title" or "Duplicate meta description" error. In my experience, most of the time this error is related to duplicate content problem.

you can use the plagiarism checker for copied content it will show you...