Andy -

Your scenario is vague as to exactly what you are doing, so difficult to 
answer.  Obviously, you don't do Backup Stgpool against a VTL: you do it with a 
primary storage pool.  We don't know whether the primary or copy is being 
migrated, or how, or if another incarnation is being created.

The guiding principles are that copy storage pools know nothing about each 
other's contents, and that the TSM database keeps track of whether a given 
primary object has such a copy in one or more copy storage pools.  Certainly, 
if you start with a fresh copy storage pool, a Backup Stgpool to it will be a 
"full" copy, without regard to any operations to pre-existing copy pools.

    Richard Sims