Uhmmmm I don't believe so...
BUT once in the ATL, the library manager tracks everything (doesn't re-read
the barcodes unless told to do so)

If you have a tape that you don't know the VOLSER here is what I'd try...

Identify a scratch tape
Check it out with remove=no
Determine the cell in which this ~checked out scratch tape~ resides (from
library console)
Switch your unknown tape with the known tape
        Oh, make sure you have inventory disabled so it won't scan the frame
you opened to switch tapes
        Now the ATL still thinks nothing has taken place...
Do a checkin libvol blahlibrary ~checked out scratch tape~ checklabel=yes
The checkin will/should fail because of a volser mismatch
        I can't say for sure but maybe the error msg will give you the
internal volser found...
                now you know what tape you really have...

Dwight