Sometimes partitions with the following structure are created:
The event data partitions are closed after two days and afterward they are compressed and archived. Events which arrive at the data storage component after two or more days are stored in new partitions where the date of when they actually arrived is appended to the end of the directory name. This gives you an indication of when events arrived at the data storage component.
For example, the following partition contains data of February 1st 2011 which arrived at the data storage component on February 4th 2011, when partition was already closed.