What is Keyword Cannibalization?
It happens when more than one landing page targets the same keyword or topic. Once a client had the urge to build one page for every keyword phrase with a decent volume pulled from the Google Keyword Planner (Adwords). The result was 2,000+ pages cannibalizing the one page I was working on. Do you want the best part? He didn't care enough to share it with me.
Not all those 2,000+ pages were competing with my page, but they were impeding its success. I have also seen cases where the keyword cannibalization is live on Google. Two or more pages were competing for the same query if you run repeated queries. The best practice before getting into damage control is professional keyword mapping. If you're in between the mess then the keyword map can serve as a guide to which pages you need to eliminate, merge, redirect, so you end up with a solid plan that breaks into topics and not keywords (that's old school SEO today highly problematic).