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Is time out a response code you are getting when querying your own website in some way? Usually it means you are crawling a site too fast and it's refusing to respond (or it can't respond in time as it has too many requests)

If you're searching for external duplicate content, like if someone has stolen your content: https://www.copyscape.com/ If you're looking for internally duplicated content: You can use SEMRush - https://www.semrush.com/ - their on-site (technical) auditing tool, also commonly comments on internal content duplication 'as' a technical SEO issue. You have to create a project for your / your client's site and then run an on-site crawl, 20,000 URLs limit recommended http://www.siteliner.com/ - Built specifically for checking internally duplicated content on your site ... or do it yourself in Excel. Commonly involves creating a grid of your site's / your client's site's content, then running Boolean string similarity with conditional formatting to generate a heat-map of content duplication. Doing the last one is a little more complex but it can come up with some super cool visuals. Right now, it relies upon the pwrSIMILARITY formula which is not native to Excel (it needs this plugin: https://officepowerups.com/downloads/excel-powerups-premium-suite/). If you don't want to pay for that I'm pretty sure that someone will probably have made a VBA script that does something similar