When updating your theme to a new version, there may be new settings or options available that have been added into the page.details template.
If you had created duplicate page.details templates prior to updating your theme, if there were new page.details features added, you won't see them by default in your duplicated templates.
This is because the Theme Updater App carries over "custom" templates identically, and will not contain any potential updates included in the default/original template.
Not to worry! You can easily update your duplicate templates to include all the new additions by following these steps (you may want to backup your theme first!):
Step 1: Head into your theme's code from the Shopify Admin > Online Store > Themes > Actions > Edit code.
Step 2: Locate the default/original page.details file under Sections > page-details-template.liquid.
Step 3: Select & copy all of the code from the original page-details-template.liquid section file.
Step 4: Replace the code in your previously created duplicate page.details section files with this code.
Once you've replaced the code in the duplicate page.details section files with the code from the original section file, the duplicate templates will now have access to the new features that have been added.