Keyword cannibalisation: why two pages on the same topic cost you rankings
Two pages aimed at the same search term compete with each other instead of with your competitor. How to spot it and which of the two should stay.
It sounds contradictory: you have three pages about heat pump costs and none of them ranks well. Meanwhile your competitor has one and sits in second place.
This is called cannibalisation. It is one of the few SEO problems that does not need new content. You need to clean up instead.
What happens
For every search, Google picks one page from your site as the best candidate. If you have three pages on the same topic, Google has to choose. Sometimes it switches, sometimes it picks the wrong one, and sometimes it spreads its trust over three pages that each get a little.
The signals that could have made one strong page are now split: the links others have made to you, the clicks, the time people spend on the page. Three half pages do not beat a whole one.
How to spot it
In Search Console you can see for each keyword which of your pages appear for it. If one search term shows several of your own URLs, often switching from week to week, you have a candidate.
Two other signs that often come together:
- A page that once ranked at position 5 and now hangs around 15, starting exactly when you published a second piece on the same thing.
- Two pages with almost the same title, where you yourself have to think for a moment about which one you would send to a customer.
That last one is the best test. If you cannot say in one second which of the two is the right one, Google cannot either.
Which one stays and what to do with the rest
Pick the page that currently gets the most traffic or has the most links. That is your base, even if another version is better written. Moving text is easier than moving links.
Take the parts the winner is missing from the other pages and add them to it. Then set up a permanent redirect from the old URLs to the winner. That way the links that pointed to the old pages keep counting.
What you should not do: simply delete the old pages. You lose everything they had built up, and visitors get an error page.
When it is not cannibalisation
Two pages on the same subject can exist side by side if they answer a different search question. “What does a heat pump cost” and “apply for a heat pump grant” look alike, but someone searching the first is comparing, and someone searching the second is almost a customer.
So the question is not whether the topic overlaps, but whether the searcher’s intent overlaps. When in doubt, type in the search term and look at what kind of pages Google shows now. That is its answer to what the intent is.
