> pair that would have used a different volume pool, but I'm not sure if
> this is going to dupe tape or images.

Paul, bpduplicate doesn't duplicate tapes, only images.  There is the
"-id <media_id>" option, but that option is only a convenience which
selects all the images that appear on the media_id specified--which is
subtly different from duplicating a tape.

Depending on the specifics of what you are trying to do and your setup,
consider that using bpduplicate directly rather than through the Vault
wrapper may be easier.  If you can script something to come up with
lists of backup IDs which should be done as a group, then bpduplicate
with a BIDfile is a natural.