TSM 5.2, AIX servers

I'm a little unclear about the intricacies of using more than one
copypool with a storage pool. There are allusions in the 5.2
Administrator's Guide to problems restoring files when no copypool has a
complete copy of a storage pool's contents. I'm a bit unclear how such a
state could come about, except in the case of a copypool medium being
destroyed.

Suppose on Monday morning, I issue:

BACKUP STGPOOL SP1 DRCP1

and it finishes normally.

Clients back up to SP1 that night.

Tuesday morning, we run:

BACKUP STGPOOL SP1 CP1

followed by

BACKUP STGPOOL SP1 DRCP1

When the Tuesday copy from SP1 to DRCP1 runs, will it copy all the files
from SP1 that have changed since the previous copy to DRCP1 ran, or will
it only copy the files in SP1 that changed since the Tuesday copy to CP1
started (or finished?)?

Another way of phrasing the question (I think) is, "does BACKUP STGPOOL
do the equivalent of an incremental backup compared to the last BACKUP
STGPOOL to the same copypool, or to the last BACKUP STGPOOL to any
copypool?"

I tried to RTFM, but either I didn't find the right FM, or I didn't
understand the answer if I read it.

Thanks,
Nick