When you have usernames in SharePoint in the format “Last name, first name” it will show up in the dispform.aspx and editform.aspx of lists with an additional comma like “Last name,, first name”.
I discovered this issue in an on premise environment and could reproduce it in Office365
The name in the User Profile is displayed correctly. In this case the Display name is imported from AD and mapped to the Name field. It can also be reproduced by changing the name manually in the User Profile.
The inconsistent display of the username also affects the search results. This is shown in the refinement panel.
Currently the case is escalated to the SharePoint Escalation Services with a RFH (Request For Hotfix). When a fix or workaround (changing AD to “First name Last name” is not an option…) is provided I will update this post
Update 19-02-2013: The escalation engineer confirmed this will be fixed in the June Cumulative Update (CU)
Rik Dekker 
Hi Nick,
I started with a new project before we were able to install the CU for this customer. To be honest I never checked if it actually was resolved by the update. I assume that you installed the June CU or SP1 (which was released last week)? If not, please do and verify if the issue is still there.
We still have the issue after installing SP2013 SP1 and CU June 2014.
This post suggests it did not come out until July 2014:
https://social.technet.microsoft.com/Forums/en-US/0e9011fe-d7ac-4004-a0ed-bc0512d9c666/issue-author-and-editor-in-dispformaspx?forum=sharepointgeneral
Thanks for the update, David