FAQ: If you have 3 nearly identical pages, why is this a problem, and what’s the solution?

If a site has 3 practically identical pages, then search engines may have difficulty identifying the main (‘canonical’) version. If they guess wrong, this can prevent the right version from ranking as highly as it should, and if they simply can’t pick a winner, this dampens the rankings for them all.

There is also a forward-planning link-equity advantage in having a single main page instead of a set of joint-main near-duplicated pages, because people will be linking to the same URL instead of link equity being spread across many. For example, if you’re expecting to gain 3 links in the near future, if you’ve defined your canonical version of the page, then your 3 new links will likely be pointing all to your main URL instead of one link to each of the 3 copies, thus giving 3 times more powerful link equity to the main copy. Of course redirects or canonical tags can consolidate link equity between near-duplicate pages at any time in a back-dated manner, but it’s not so seamless as when all links are already pointing to the main version to begin with.

Due to your content being more unique between indexable pages after you’ve sorted your canonicalisation issues out, your site also has less of a spam factor — a higher content quality score overall.

Note that if your 3 pages were slightly less unique, but still too similar for desirability, ‘keyword cannibalisation’ becomes the issue.

Solution

One potential solution would be to use the rel=”canonical” tag to identify the preferred version of your near-duplicated page. This is the right solution if separate pages are really needed for site functionality or personalisation, but often your duplication issue occurs in error, due to some versions being a bit older, or the site code being messy, in which case the best solution (where possible) is actually to pick a canonical (preferred) version (URL) of the page and then do a HTTP 301 (permanent) redirect from all the others versions to the chosen one. Canonical tags consolidate equity well but not perfectly, while 301 redirects are more definitive and universal, although nothing beats avoiding excessive duplication in the first place!