Two entries with the same value for atom:updated
Date values SHOULD be as accurate as possible. For example, it would be generally inappropriate for a publishing system to apply the same timestamp to several entries which were published during the course of a single day.
Ensure that these atom:updated entries are as accurate as possible. This check is not something that can be automated.
If the two atom:entry elements in question were updated at the same time, then no action is necessary.