Why can i add /page/674874 (or any number) to a URL and it still pulls up that page?

I have noticed that on any WordPress site you can add /page/7863/ (or any number) to any page url and it still shows that page and not a 404. Why is that? (Asking because my SEO company sends reports that show /pages/(number)/ as different pages even though they are the same page just different number as shown in screenshot)

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