How to check duplicate content issue in SEO?

[jjthemanjunaid]

How to check duplicate content issue in SEO?
I would like to know how to check duplicate content issue in SEO?

[davidweb09]

use copyscape.com free to check duplicate content in your site.

[servermonitor]

Which content you feel as duplicated, copy the first line of that content and google it. If you find your content is placed in many pages from those results, then you have duplicate content issue. Another way to find duplicate content is by using copyscape.com

[rajusrivasvt]

Use copyscape.com to check duplicate content.

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[josephinek]

Use,
>google webmaster tool
>smallseotools.com
>plagspotter

[CurtisField]

Few tools generally used to check the duplicate content issue in SEO these tools are such as Copyscape, Google Webmaster Tool, SmallSEOTools,
duplichecker etc.