User appears 2 times in his profile when Message Stream is activated

Steps to reproduce:

1. Log in as Admin
2. Enable Message Stream (Administer Wiki > Other > Message Stream > Yes > Save)
3. Create a new user (Administer Wiki > Users & Rights > Create user)
4. Click on the username to go to the profile of the newly created user (or search for username)
5. Observe the users listed in the Send Message section

Expected results: The users present in the wiki are listed.

Actual results: The user that is accessed appears with his username and also as ""xwiki:XWiki.user01"