If you are trying to add a Pages List to your Blogger site using the latest version of the Blogger interface, you may come up against the oddity of the gadget selection tool telling you it is “Already Added”
No matter where you look, or what you click on in your layout settings, you just cannot find it?
Fear not! This appears to be a slight misalignment of the old Blogger interface to the new one.
Navigate to the pages option on the left hand side of the screen…
Click the “Don't Show” button, and from the drop down, select either “Top tabs” or “Side links”
Now most importantly, click the “Save arrangement” button in the top right corner. Not doing this, will cause the modification made in the previous step to go unapplied.
A “Pages” section will then appear on you site when you return to it, you can click the Spanner/Screwdriver icon to alter various aspects of the gadget.