Why are two of my pages competing with each other?
Cannibalization is when several of your pages answer the same question. Google cannot show both, so it picks one — often not the one you would choose — and the position starts swinging between them. The fix is almost always merging, not optimising.
The symptom is simple: Search Console shows different URLs of yours appearing for the same query on different days.
How it happens by itself
Usually not through carelessness but through time. An article written two years ago, a section of a service page updated last year, and an FAQ added this year — all three answer the same thing.
The second source is technical: the same content reachable at several
addresses (with and without a trailing slash, with and without a parameter)
and no canonical.
How to check
Search Console → Performance → filter by the query and look at the "Pages" column. More than one of your URLs there means cannibalization.
The second way is a site:yourdomain.com keyword search. If you see three of
your pages about the same thing, Google sees the same.
What to do
Merge. The best option: keep the strongest page, move the content of the
weaker ones into it, and 301 the old URLs. Link equity then collects in one
place.
Separate. If both pages have a right to exist, they must answer different questions. "SEO audit" and "SEO audit pricing" are two topics, not one topic on two pages.
Canonical. When the duplication is technical, canonical says which
version is real. That is a fix for duplicates, not for competing topics.
What not to do: keep both and "optimise" both. That only strengthens the competition.
A free scan shows repeated title and description values and pages
whose content is very similar — the first sign of cannibalization.
Frequently asked
Is this a penalty?
No. Google simply picks one of your pages. There is no penalty, but there is no stable position either.
Does `noindex` solve it?
It ends the competition but throws away link equity. A `301` to the stronger page is almost always better.
How similar is too similar?
The line is not a percentage but a question: if the same query would lead to both pages, they compete.
Does a category page compete with an article?
It can, if both target the same thing. A healthy rule: the category answers "what options exist", the article answers "how to choose".
Check yours
A free scan shows which of the things described here your site already does, and which it does not.