There are two types of keyword cannibalism. The first is related to organic SEO (search engine optimization) methods, and the second has to do with PPC (pay-per-click) advertising. Let’s look at both types and how to avoid them.
This ominous term can best be defined as a website having multiple pages and sub-pages that heavily target the same keyword.
Here is an example: take a keyword like “chocolate bar.” You sell your delicious, organic, homemade, solid chocolate bars online. When you created your website, you made sure that every page title, header text, meta description, image alt tag, etc. included the keyword “chocolate bar.” By using this tactic, Google will have no idea which page is the most relevant page to display on search queries for chocolate bars. Google might choose your "About" page to display, but is that what you want? Hopefully you answered no, and when people are searching for chocolate bars, Google will display your product page.
Option 1: First, NEVER use just one keyword for all of your website pages. Instead, do your keyword research and find out what keywords perform well in your industry and use them throughout your site whenever they are relevant. Also, use variations of each keyword you decide on. Google will then be able to index multiple keywords for your site.
Option 2: Use canonicals link elements. Obviously a more technical approach and one that involves adding additional text to the head section of the related web page. Google provides ample support on how to use this element, so I won’t bore you with the specifics on how to implement canonical link elements.
The concept of keyword cannibalism is a little different when it comes to dollars being spent on keywords. Let's take a look again at your chocolate bar business.
Your website ranks well for “Chocolate bars,” and sales are great. Recently, you created a new chocolate and peanut butter bar that you want to start promoting using paid online advertising. Some of the obvious keywords you might use are, “chocolate and peanut butter bar,” “chocolate and peanut butter,” “chocolate peanut butter bar,” and so on. You also use "chocolate bar," but worry because you don’t want to pay for something you already rank well for, organically.
The good news is you don’t have to. Google’s algorithm accounts for words you rank for organically, versus the current paid campaigns you're running. Google also conducted a rather thorough study that concluded paid keywords do not cannibalize ranked keywords for businesses and websites.
Your main takeaway from this blog should be to do your keyword research, use variations of your keywords throughout your web pages and blog post and you’ll avoid cannibalizing yourself.