Hi there,
When importing large numbers of Collection items via CSV, it’s important to take proper precautions. First, create a backup of your site in the Designer before starting the import process. During the actual CSV import, you can skip the backup step by clicking “No” when prompted.
For the import itself, you have two options: “Update matching items” or “Import all items as new items.” Choose “Import all items as new items” if you want to ensure every entry is created as new, regardless of potential matches with existing items. You can learn more about managing backups in our University guide.
Hopefully this helps! If you still need assistance, please reply here so somebody from the community can help.