Defining duplicate content

A search engine considers every unique URL to be the location of a single web page. It learns about such URLs by following links. Duplicate content occurs when a search engine follows more than one unique URLs that take it to a page of predominantly similar content – these pages do not need to be identical, just very similar (a defined ratio is something of a holy grail for optimisers and not clearly established).

Why is this important? A search engine will not display more than two pages from a website for a particular search. It makes an automated decision of which pages are the authoritative or originating version of that content, tucking the rest away at the end of the results: the Supplementary Index.

The damage to SEO comes from a number of factors, the two main causes being:

1. The page you most want to surface may become inadvertently pushed into the Supplementary Index, thus giving searchers an inferior, poorly converting page to visit.
2. A major factor in search result visibility is the number (and quality) of links pointing to a page, but multiple URLs to a page frequently dilutes the combined effectiveness of back-links as the links point to different unique URLs. 

From my direct experience with sites over the past year in particular, duplicate content pages result in a cumulative deterioration of the entire site’s visibility in SERPs (Search Engine Result Pages). 

If you have a site that is failing to rank well for even the least competitive search terms, such duplicate content is likely to be a contributing factor, and you will struggle to establish a firm footing until this problem is resolved.

Spotting the damage

Discovering duplicate content is relatively straightforward. Perform a search for your website on Google, like this:

site:yourdomain.com keyword

where yourdomain.com is your website’s domain, and keyword any terms for which you are trying to be visible. Run down to the very end of the results and if you see a message like this:

you have duplicate content!

The cause

Content Management

If you have a duplicate content issue, then I will bet your website runs on some form of content management. Blog applications are notoriously prone to these problems, with supplementary listing pages such as category summaries, tag summaries, archive lists, and search results, all in danger of generating pages with very similar content.

In addition, some content systems do not chose a single means of generating a URL for a item of content, linking to pages and posts in slightly different ways from different parts of the system. They may also fail to redirect all URLs to the canonical URL for that page or post.

Identical meta data

In addition, it is very common to come across sites with many – sometimes even all – their pages with identical titles and META descriptions . This is particularly prevalent once again with blogs, and also in the small business space where a company feels it must apply its company name and corporate blurb at the top of every page, thus not accurately reflecting that page’s actual content.

Page titles are very important in establishing the context of a page, and must be unique in order for the search engine to properly understand the page content.

Too little unique textual content

Pages with little unique text content can become regarded as duplicative because the majority of the content there is similar to everywhere else on the site. In these sparse content examples, the site-wide navigation, footer information, and other generic text, can form the majority of the textual content.

Search, archive and summary pages

As mentioned above, pages that summarise and list snippets of other content can easily appear to a search engine to be very similar but have unique URLs.

www and non-www domains

This one often surprises web developers, but www.yoursite.com is, to a search engine, a different website to yoursite.com. This means that if all your content is reachable via both those versions, your entire site is seen as being a duplicate!

It does not matter which you choose, but have one of those URL versions permanently redirected to the other.

Repairing the damage

Now that I have covered most of the indicators and causes, how about a means of fixing the problem? Watch out in a few days for specific techniques to repair and remove duplicated content within search engines.

Every link must count

Link building effort, whether as a result of active placement of links yourself or by other sites organically lining to your great content, is impotent if the search engines are not aware of the page linking to you, and therefore not aware of the link. Most advice on link building you’ll find around the web, excludes one critical, additional task: ensuring pages that link to you are indexed in the search engines.

If you create the link yourself in whatever method, you will be aware of where that link has been placed – providing you are sensible and record the locations of your links, of course. But what about organic links, how can you discover where they have been placed?

Who links to you?

If a search engine already knows about a page that links to you, all is well and there’s nothing more for you to do. To discover which links fit into this category, simply perform a search in the following format: link:yourdomainhere.com. Every page returned will have within it a link to the domain you entered. But what should concern you are the pages that link but do not show from this search.

Logs, logs, logs

Whatever system you choose, whether it be visitor traffic logs provided by your web host, the free Google Analytics, or some other logging service, you should be able to access detailed lists of refers: where people came from when they visited your site.

Scour your refer logs and check every site you have not already checked (you’re keeping records, right?) to see if that page is in the search engine index. Do this by placing the entire page URL as a site search, like this: site:referdomain.com/page-that-sent-the-visitor.html. If no pages are returned, then that page is “unindexed”.

Linking out

The best way of letting a search engine know about a site or page is to create a link to it. When you discover an unindexed refer, link back, it’s as simple as that!

Where you place that link back might depend on the structure of your site, or you may want to place the link back on a completely different site to avoid direct reciprocal – or two-way – linking (managing non-reciprocal linking like this is a whole other subject and beyond the scope of this post). In its simplest form, create some kind of “Sites that link here” page, containing all the unindexed refers you have found.

Check them after a couple of weeks and if the page has found its way into the search engine, remove the link from your site.

Time and effort

Scouring through refer logs for unindexed pages may seem a troublesome task, but with the amount of effort needed to link build in the first place, it is vital to squeeze as much value from that effort as possible.