Same-document reference(s) in multiple Collections

As I understand it, I can only move a selection of (one to all of) a Collection’s referenced items.
If so, this may be a problem for me when I convert a Collection to a pre-draft document set for further development.
(For me, Collections are stacks of ideas as demonstrated by particular texts, not of specific statements.)

If I move from a Collection one or more of its referenced items that happen to be already in an established purposeful set of ‘real’ documents, I run the risk of pulling real documents from my current works in progress for the sake of the new effort.

If indeed I can now only move a selection of referenced documents, it would be of use to be able also to copy (or ‘duplicate’) them into a new actual-document set as new documents, so that their manipulation does not gut already established document sets.