You can't as Joomla needs username, user id, and email address to be unique. You can't have duplicates of either one of them. You'd need to massively modify Joomla and CBs core code to allow duplicates and even then it may not work (please note I can not help you with core edits).
Kyle (Krileon)
Community Builder Team Member
Before posting on forums:
Read FAQ thoroughly
+
Read our Documentation
+
Search the forums
CB links:
Documentation
-
Localization
-
CB Quickstart
-
CB Paid Subscriptions
-
Add-Ons
-
Forge
--
If you are a Professional, Developer, or CB Paid Subscriptions subscriber and have a support issue please always post in your respective support forums for best results!
--
If I've missed your support post with a delay of 3 days or greater and are a Professional, Developer, or CBSubs subscriber please
send me a private message
with your thread and will reply when possible!
--
Please note I am available Monday - Friday from 8:00 AM CST to 4:00 PM CST. I am away on weekends (Saturday and Sunday) and if I've missed your post on or before a weekend after business hours please wait for the next following business day (Monday) and will get to your issue as soon as possible, thank you.
--
My role here is to provide guidance and assistance. I cannot provide custom code for each custom requirement. Please do not inquire me about custom development.