Keyword cannibalization means that you have various blog posts or articles on your site that can rank for the same search query in Google. Either because the topic they cover is too similar or because you optimized them for the same keyphrase. If you optimize posts or articles for similar search queries, they’re eating away at each other’s chances to rank. Usually, Google will only show 1 or 2 results from the same domain in the search results for a specific query. If you’re a high authority domain, you might get 3.
http://sites.gsu.edu/jsalters2/1-problem-definition/comment-page-691/#comment-49983
https://neuro.informatik.uni-ulm.de/PSL2013/?page_id=14#comment-199888
http://fatcow.com/blog/?p=1404#comment-2993231
http://www.yaldatuhls.com/yalda-panel-2/#comment-121451
https://www.theroastedroot.net/tropical-white-sangria-naturally-sweetened/#comment-346373
If you cannibalize your own keywords, you’re competing with yourself for ranking in Google. Let’s say you have two posts on the exact same topic. In that case, Google can’t distinguish which article should rank highest for a certain query. In addition, important factors like backlinks and CTR get diluted over several posts instead of one. As a result, they’ll all probably both rank lower. Therefore our SEO analysis will give a red bullet whenever you optimize a post for a focus keyword you’ve used before.
Checking whether or not your site suffers from keyword cannibalism is easy. You simply do a search for your site, for any specific keyword you suspect might have multiple results. In my case, you cannibalize your own keywords, you’re competing with yourself for ranking in Google. Let’s say you have two posts on the exact same topic. In that case, Google can’t distinguish which article should rank highest for a certain query. I’ll google site:yoast.com readability ranks. The first two results are the articles I suspected to suffer from cannibalization.
https://www.bunity.com/air-comfort-technology-6268dc719dfbc8dae03cf6c8
https://www.b2bco.com/aircomforttechnology
https://www.usbusinessdirectorylistings.com/listing/air-comfort-technology-2/
http://www.travelful.net/location/4884576/nuited-stats/air-comfort-technology
http://www.askmap.net/location/6181137/united-stats/air-comfort-technology
https://www.freelistingusa.com/listings/air-comfort-technology-1
https://www.techdirectory.io/windermere-fl/autotech/air-comfort-technology
keyword cannibalism can also occur if you optimize posts for focus keywords that are not exactly, but almost the same. For instance, I wrote two posts about whether or not readability is a ranking factor. The post ‘Does readability rank?‘ was optimized for [does readability rank], while the post ‘Readability ranks!‘ was optimized for the focus keyword [readability ranking factor]. The posts had a slightly different angle but were still very similar. For Google, it is hard to figure out which of the two articles is the most important.