I want to know what is the effect of duplicate content on same website. For example, there are two pages, one is about Delhi and other is about Mumbai. All the content is same except the titles and heading. Title: IVF Treatment in Delhi / IVF Treatment in Mumbai Heading: IVF Treatment Centre in Delhi / IVF Treatment Centre in Mumbai Difference is only 'Delhi' and 'Mumbai' Please guide.
This is a big no no. Each page should be unique. What you're doing right now is writing content for search engines instead of humans. It's viewed as being spammy and can negatively impact your rankings.
At the point of google you must follow content policy. But in your case i think this is not a big issue. You need unique content for each page and you can use title as you want like delhi or mumbai as you want