“-2” Being added to end of URL (no duplicate pages, no pages in trash)

Duplicates don’t just come from Pages and Posts, WordPress also defines Images and Files from the Media Library as “Posts”. This means if you have a file / image in the Media Library with the same name as a page, it will assign the next duplicate a -2 ( from the wp_unique_post_slug() function ) so there’s no URL conflicts.

TL;DR – Duplicate? Search for Pages, Posts, and Images.