There are some scenarios in which you may want to allow a number to be uploaded multiple times against different names (e.g. a school that needs to contact a parent on one number but referring to two different children in separate messages).
By default, the Web Portal will automatically restrict duplicate numbers from being uploaded; however, this can be changed to allow duplicate numbers to be uploaded
Go to Account, then Account Settings. To allow duplicate contacts, click on the toggle switch next to Allow Duplicate Contacts:
NOTE: Once you have turned this on, you will need to contact support (email@example.com) if you want to turn it back off.