Universal properties created prior to December 2013
Universal properties created prior to December 2013 may temporarily report doubled Visits counts between the hours of 0500-0800 in the View timezone. This issue corrects itself automatically. We are working on a fix to address this issue as soon as possible.
— Google Analytics.
This is a problem as it literally double counts the number of visitors, making comparisons nothing less than impossible because not all visits were double counted.