A backup or duplicate job to a deduplication folder fails because it thinks there is already media in the virtual drive.
A cache coherency problem occurs when multiple servers are accessing the same target deduplication device. One server finishes using the virtual drive in the deduplication folder and removes the virtual media, but the other server doesn't recognize the change. When the other server attempts to use the virtual drive, it thinks there is still media in it, and produces the error.
When this error occurs, a line such as the following will be placed into the adamm.log file.
 12/04/12 23:21:33.316 DeviceIo: ostscsi: Image 144 is already in drive 2
A hotfix is now available for this issue in the current version(s) of the product(s) mentioned in this article. Refer to the Hotfix link under Related Documents at the end of this article to obtain the hotfix needed to resolve the issue.
Backup Exec 2010 Rev 5204 Service Pack 3 (TECH203157)
Backup Exec 2012 Rev 1798 Service Pack 2 (TECH203155)