Unique
The Unique property prevents the duplication of current content across entries in a content type.
Note: The Unique property works only for content types with “Multiple” entries.
When you add a field to a content type and set it as Unique, that field will only accept non-duplicate values. If a user enters an existing value, they will get a prompt to change the duplicate value.

- If a field is marked as Multiple, then the Unique property will not be applicable.
- You can save the entry even if non-mandatory fields that are marked as “Unique” are left empty.