Look for the same promise
Compare the headings, the core content and the target action. If two pages offer the same service to the same people on almost identical terms, keeping them separate may be pointless. Swapping in a few synonyms doesn't create a new answer.
At the same time, an article on when you need a CRM and a CRM implementation service page have different intent. They don't need to be merged just because they share an acronym. It's better to clarify their roles and connect them with a relevant link.
Check queries and URLs together
See which URLs get impressions for closely related queries over a comparable period. A page switching places in search results doesn't prove a problem on its own. You need a link to an ambiguous structure and too little difference in content.
Account for seasonality, new posts and redesigns. Don't make an irreversible decision based on one short ranking fluctuation. Save the original data so you can check again later.
Choose one of two fixes
If the intents differ, strengthen the differences: headings, questions, examples and internal links. If the answer is the same, choose the main URL, move the useful content over and set up a redirect from the old page.
An SEO audit helps tell real duplication apart from normal topical overlap. In ongoing SEO work, keep the topic map up to date before every new series of articles so you don't pile up identical answers.
