Has anyone figured out a valid use for these yet? Every idea I originally had for them has failed due to the stacking mechanics. I'll list my failed endeavors below.

Usable cores from the Confluence have different values and therefore don't stack.
Charged magic items (even when they have the same number of charges), also seem to have variable values and result in them not stacking.
I even attempted stacking magic items I bought from a merchant who charged up imbeds during Ebon Gate. These items all look and cost the same, and he filled them to 20 charges a piece. They would not stack.

One use I could possibly think of is straight store bought magic items (like those spell crystals for magic item use jewelry), but I didn't have any of those to test. And it's also something I don't need in general.