You can definitely add the same zone in multiple spots on the same page.

However, if there is only one campaign placed into that zone, it’s possible you may end up only seeing the zone appear once. If that happens it would be because the adserver makes sure the same campaign isn’t shown more than once on a page.

If that is occurring, you’ll want to be sure to either set your campaign to allow repeating (choose the right option for you! You can read through the different options here), or edit the zone to “Allow Duplicates” in the zone settings.