Topic
The Remove Duplicates from Collection action takes note of the value in each index starting at zero and will remove a value from the collection if it is found again. This functionally is handy when creating mailing lists or any other process that requires only unique values in a collection variable.
Please see the Nintex Help files for more information:
https://help.nintex.com/en-US/nwc/Content/Designer/Actions/Collection-RemoveDuplicates.htm