Duplicate content: what it is and how to fix it

What counts as duplicate content?

There are two kinds. With exact duplicates, exactly the same content sits at different addresses. With near-duplicates, the pages differ by only a few words, for example just a town name or a product colour. To Google they amount to the same thing: the pages add little compared with each other.

Repeated parts that appear on every page, such as your menu, footer or a short disclaimer, aren't a problem. Google understands that's part of a website. It's about the main content of a page.

How does duplicate content end up on your website?

It's usually not a deliberate choice, but a technical side effect. These are the best-known causes:

• Your site can be reached both with and without www, or via both http and https.
• The same page with and without a trailing slash, or with upper- and lower-case letters.
• Parameters in the URL, for example from filters, sorting or ad campaigns, such as ?sort=price or ?utm_source=newsletter.
• Print versions or separate mobile versions of pages.
• A product that sits in several categories and gets its own URL in each category.
• Test environments that are accidentally open to Google.
• Pages per town or service that are identical apart from one word.

And then there's the variant outside your own site: text you copy from a supplier, or text others copy from you.

Is duplicate content bad for SEO?

There's a persistent idea about a 'duplicate content penalty'. In practice, Google doesn't penalise ordinary websites for technical duplicates. Google simply filters them out. Only when someone deliberately copies text on a large scale to mislead Google might Google step in.

The real downsides are more subtle:

• Google may show a different URL than you want, for example a version with parameters.
• Links and signals are spread over several versions instead of being bundled on one page.
• On large sites, Google spends time on duplicate pages instead of on your new content.
• With near-identical pages, Google may see all of them as low value.

Checking for duplicate content: how to find it

You can track down duplicate content in a few ways, even without paid tools.

• Look under Pages in Google Search Console. Messages such as 'Duplicate, Google chose different canonical than user' point straight to the problem.
• Type site:yourdomain.nl into Google with a snippet of text in quotation marks. If you get several URLs from your own site back, the text appears twice.
• Do the same without site: to see whether other websites are using your text.
• Test for yourself whether www, without www, http and https all redirect to one and the same version.
• Let a crawler run through your site. It shows pages with the same title or description, often a sign of duplicate content.

Fixing duplicate content: four ways

Which solution fits depends on the cause. Choose case by case:

• 301 redirect: use this if the duplicate URL doesn't need to exist. For example with www and non-www, http and https, or an old page that's been replaced. Visitors and Google go to the right version automatically.
• Canonical tag: a piece of code that says 'the real version of this page is over there'. Handy when the variants do need to stay, such as filter URLs or a product in two categories.
• Noindex: asks Google not to include a page in the search results. Suitable for pages you need but that don't belong in Google, such as internal search results.
• Rewrite or merge: if two pages cover the same topic, turn them into one strong page. Or give each page genuinely its own content.

A common mistake is using everything at once. A page with a noindex and a canonical pointing to another page gives conflicting signals. Choose one clear approach per page.

Other people's text: suppliers, press releases and AI

Duplicate content also arises when you use text that's already online elsewhere. Think of product descriptions from a supplier, a press release that appears on ten news sites, or generic text you had an AI tool write that resembles what's already everywhere.

• Don't copy supplier text word for word. Rewrite it in your own words and add your own experience.
• Post a press release on your own site first and let others link to it.
• Use AI text as a rough draft at most. Add examples, prices and knowledge only you have.
• If you also publish an article on another platform, such as LinkedIn, put it on your own website first.

That way your page stays the source Google wants to show.

Special cases: online shops and pages per town

Online shops suffer from it most, because of filters, variants and supplier text. In our article on SEO for online shops you can read how to deal with that.

Another risk is local pages. Many businesses create a page per town with the same text and only a different town name. Google sees such pages as doorway pages: pages that only exist to appear in search results. They don't help you and can even harm your site. You can read how to do it properly in our piece on pages per town.

Preventing duplicate content on a new site

The easiest thing is to prevent duplicate content from the start. On the websites Violexa builds, we handle this in the technical setup as standard: one fixed version of your domain, clean canonical tags and no test environment open to Google. It's part of the basic SEO of every custom website, from €1,799 excl. VAT (€2,177 incl. VAT).

Not sure whether your website suffers from duplicate content? Book a free quickscan. In a 30-minute conversation, online or on site, we go through your site together. You get brief written advice with a price indication, with no obligation.

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