multiple Media IDs for same tape?

[sling]

I am a new Backup Exec 12 for windows server user. We recently purchased a new server from dell.
There are 3 server tapes being used by Backup Exec. It will automatically change the Label and assigns a new Media-ID
(Which I thought can't be overwritten or changed) to the tape.
This happens pretty much every time the backup runs, and my media pool keeps growing

Anyone has an idea what happens?

[Larry_Fine]

The tapes shouldn't get a new ID or label automatically.  The label can be changed by running a "label" job.
Is this a stand-alone drive or a robotic library?  Can you supply more details?

[sling]

Sorry for the late reply, I had a long weekend. 

It's a Removable Backup-to-Disk Folders.  Because the backupexec won't able to add the DELL RD1000 as a stand-alone drive or a robotic library.

Also I notice there is another weird thing to the backup media. For instance, if I inserted a backup tape (label “Tape 3”) to backup 34Gb data, When the backup completed, “Tape 3” is disappear from the media list, instead there are two new Labels like “BT0004” “BT0007”. 

                           Allocated date                                   data
BT0004         6/4/2009 7:00:08PM                          13.5GB
BT0007         6/4/2009 7:00:06PM                           21GB

However, The job history shows only one job completed.

Any sugguestion???

thanks