One possible way is to make a change is to create two tapes with the same
tape name and enter them into the slots.   The way the system looks at is
the tapes are still there.   Because they were not checked out properly.
You need to somehow make the system believe that you are checking out the
tapes.   If you look into the devconfig file, it might show you if the two
tapes are shown to be in the slots.   If so you could also make a change to
that file that shows two other tapes are in those slots.   Then insert the
correct tapes in the correct slot.   I have done something like this before,
but I also use a 3570 tape device.