What about not multiplying the quanta that gets stored, at all? Just being able to store the quanta seems to be worthwhile in certain strategies.
This is just what I was going to say:
1:
The quanta duplication would definitley make broken decks with Cremations and Hypernovas.
2:
It would be a super powerful card even without the quanta duplication:
. Double Fractal
. Double Sky Blitz
. Quanta denial counter
Of course, the counter to the card would be Steal/Destroy.
3:
You must clarify what happens if a player plays 2+ caps and what happen if one of them is destroyed when the other one is still in play. A viable solution would be only count the first cap in play, and if it's destroyed another cap begins to be the quanta accumulator.