In the databases window, "Last Differential Backup" values are incorrect for all databases that have never had a diff backup, showing the last full instead of null. Likewise, "Last Log Backup" values are incorrect for all databases that have not had a log backup (e.g. ones with "simple" recovery). For SQL Server 2000 databases, this causes an alarm.
We have changed something for database backup in version 11.1 (reference SOSSE3952)
log backup time = most recent of Full, Diff or Log backup time
Diff backup time = most recent of Full, Diff
Because a full backup will also back up transaction log. This is why the databases window showing the last full instead of actual diff or actual log.
This is not accurate enough, so we have submitted enhancement request to have a new column added to state last real log backup or others (request reference SOSSE4205)