News Courtesy of Yoast.com:
Keyword cannibalization means that you have various blog posts or articles on your site that can rank for the same search query in Google. If you optimize posts or articles for similar search queries, they’re eating away each other’s chances to rank. Here, I’ll explain why keyword cannibalism is bad for your SEO, how you can recognize keyword cannibalization and how to solve it.
What is keyword cannibalization?
If you optimize your articles for similar terms, you might suffer from keyword cannibalization: you’ll be devouring your own chances to rank in Google. Google will only show 1 or 2 results from the same domain in the search results for any specific query. If you’re a high authority domain, you might get away with 3.
Ryan’s Take 
It sounds like a vicous term; keyword cannibalization. However, what Yoast describes is a pretty accurate assessment. It doesn’t make much sense to have multiple articles describing the same topic. Honestly, I’m probably guilty of this too. I think that 2 or 3 pages might be okay. Anything more and those pages are competing with one another.
What if you talk about a broad subject on multiple pages but the difference is that they focus on other sub-topics? Take for instance my two lengthy pages on SE Ranking. Both are reviews concerning that SEO tool, however, they each focus on different areas of that tool. The first review is all about competitor spying and research tools. The second review details information on keyword tracking and tools to help optimize your target website.
It is that second review which gets priority placement in Google. It could be because it is the more recent of the two, but also it has about 600 words more in content. When I type in “SE Ranking Review” my page fluctuates in the rankings. It’s gotten as close as position #31. Not even close to the first page.
So, let’s put Yoast’s suggestion in action. Today, I’ll be combining the two pages into one. It makes more sense to take the content from lower ranked paged (1st review) and place it into the higher ranked page (2nd review). That should give me a total word count of 4300 or so. About 500 more than another excellently written competitor’s review.
The top spot belongs to G2 Crowd. Currently clocking in at 22,000 words, there is no way I could reasonably expect to outrank them. They have the advantage of taking user-submitted reviews and adding it to that page. However, I plan to use that to my advantage. Since I also have Precise Online Management listed on G2 Crowd, I will write a review from my company’s standpoint on SE Ranking. It is something I have been wanting to do but kept procrastinating on. Of course, my profile is linked to my company’s homepage which should factor into Google’s Ranking algorithm. We’ll see!
