I was feeding a bunch of old history-data into zabbix with zabbix_sender (byte-size of database-dumps).

I created custom timestamps for each value so that i get the same time on each day the backup was taken, but when checking the history for this key, the values are not the same as i was feeding it.

Here is an example:

echo "<host> <key> 1262318400 25778177" | /opt/zabbix-1.8.3/usr/sbin/zabbix_sender --zabbix-server <server> --port 10051 -T -i -

this get's displayed in the history of the item as: 2010.Jan.01 05:59:58 26396853248

The timestamp i was feeding: 1262318400 is 2010.Jan.01 04:00:00