Event ID 644 - Locked Out Report contains duplicate entries

Event ID 644 - Locked Out Report contains duplicate entries

We have a daily report which reports on event 644 occurences (Windows user locked out).  For some reason our report contains duplicate entries for the same user. 
 
* It has the same time stamp
* It is from the same source server
 
This is an intermittent issue.  Can anyone advise on why this occurs?
 

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