If you hire an SEO company and later discover that the work it produced has created duplicate content on your site, you have a real problem to address and a vendor to hold accountable. This situation is different from a company simply explaining how it manages duplicate content in general. Here it has caused the issue, and that affects both how you fix the site and how you handle the relationship.
How the duplicate content harms your site
Duplicate content is when the same or very similar text appears on more than one URL, either within your own site or copied across other sites. Google does not issue a specific penalty for ordinary duplicate content, but it still hurts you. When Google finds several near-identical pages, it picks one version to index and treats the rest as alternates. That means pages you paid to have created may never appear in search results. It also splits ranking signals across multiple URLs instead of concentrating them on one strong page, and it wastes the time Google spends crawling your site on pages it will not use. The practical result is weaker visibility for content you already paid for.
An SEO company can create this problem in several ways: publishing thin location or service pages that differ only by a city name, spinning one article into many slight variations, copying text between a hub page and its subpages, or generating bulk pages with templated text that repeats across hundreds of URLs.
How to identify it
Before you can fix anything, document the scope. Use Google Search Console to review the Pages report, where Google flags URLs it has not indexed, including alternates with a canonical it chose itself and pages marked as duplicates. Run a site crawl with a tool that detects near-identical pages. Search a distinctive sentence from one of the new pages in quotes on Google to see how many of your own URLs return it. Keep a written record of the affected URLs, because you will need it both for the fix and for the conversation with the vendor.
Fixing the site
The right fix depends on whether the duplicate pages serve a real purpose. If only one version should exist, consolidate. Use a 301 redirect from the duplicate URLs to the single page you want to keep. A redirect is a strong signal to Google, passes most ranking equity to the destination, and is the cleanest choice when a page is being retired for good.
If a duplicate URL needs to stay live for users but should not compete in search, add a rel=”canonical” tag in the page’s HTML pointing to the preferred version. A canonical tag is a strong hint rather than a command, so Google can override it if other signals conflict, and suppression of the duplicate can take several weeks. Apply only one canonical tag per page, point internal links to the version you want indexed, and avoid canonical chains where one page points to another that points to a third.
If the pages exist only to pad the site and have no real value, the better answer is often to rewrite them so each page is genuinely distinct, or to remove them entirely. Canonicalizing or redirecting hundreds of thin templated pages does not turn weak content into strong content.
Holding the company accountable
Treat the cleanup as a deliverable the vendor owes you. Share your documented list of affected URLs and ask the company to explain how the duplication happened and how it will correct it at no extra charge, since fixing its own defect is not new work. Ask for a written plan that names the consolidation method for each group of pages and a timeline. Review your contract and any scope or quality terms, because publishing duplicate content can be a failure to deliver work fit for purpose. If the company resists or repeats the pattern, that is a strong signal to consider a different vendor and to ask for the cleanup to be completed before the engagement ends.