It may negatively affect your website SEO and you aren't aware of it. If you target the same keyword on two or more pages of your website, you will confuse the search engine. It makes it difficult for search engines to decide which pages to rank.
There are three problems of Keyword cannibalization are as follows:-
1. Same Keyword:- If you target the same keyword on multiple pages then you can't control which pages the search engine will rank. For example - If you want to rank the service page Google will prioritize the blog section page.
2. Confusion while creating internal links:- If you target the same keyword on multiple pages. You are generally getting confused about where to take users when an internal link is created using that keyword.
3. Wasting a good opportunity:- On every website page you can target two keywords actively but if you use the same Keyword on two pages then you are wasting the opportunities to use one or more keywords on the same webpage.