Nineteen pages with the same name

On a recent audit, nineteen pages of one site shared a title with at least one other page. Not similar titles — the same string, letter for letter. The owner had never noticed, because no page looks broken. Every one of them loads, looks right, works. The damage is entirely on Google’s side of the glass.
What Google does with twins
When several pages carry the same name — or worse, the same body — Google does not rank them all. It clusters them, elects one representative, and files the rest away. They are not penalised; they are collapsed. Your carefully separated product variants, location pages or paginated collections become, from search’s point of view, one page with extra steps.
The election is not yours either. Google may pick the paginated second page as the representative, or the variant that is out of stock. The value you meant to spread across nineteen pages concentrates in one you did not choose.
How sites get here
Almost never by carelessness. Templates do it: every collection page inheriting the shop name, every variant inheriting the product title, a pagination system that appends nothing. The platform fills the field so the field is technically filled. Uniqueness is nobody’s job, so nobody does it.
The repair, in priority order
First, find the twins — a crawl comparing every title on the site takes minutes and is exactly what a whole-site audit is for. A one-page speed test will never see this problem; it lives between pages.
Second, decide which twins are real duplicates and which are distinct pages wearing the same badge. Real duplicates get a canonical link pointing at the one true version. Distinct pages get titles that say what makes them distinct — the variant, the location, the page number, the thing a searcher would actually type.
Third, check the bodies. If two addresses return identical content byte for byte, no title will save them; consolidate or canonicalise. The goal is simple to state: every page either has a reason to exist in search, or points honestly at the page that does.