Scenario1: Single credential scenario
Table below covers how email sync works between AH and Identity Stores
If the flow happens as described in the table above, the is no change for a user to have multiple email addresses.
Scenario2: Multi credential scenario
Below is the only scenario where a user can have multiple credentials in AH
The only difference between scenario1 and scenario2 is after step5. As long as the flow described in scenario1 is followed, a user will have a single credential for a type (email/phone). If a user ends with multiple creds of same type then AH admin console can be used to delete unwanted credential