Dual Exposure

Did you try to make the cubes non-collidable to the player only by default?
Would make jumping/flying on them not possible. Only the first cube gets non-collidable, once it's locked/glued on place (in air if it hits us)

I would suggest changing the color or another attribute when cubes duplicate as it was unclear at first. Maybe by writing some logo onto the cubes ?

I really like what you're going for! The duplication concept is really unique! It's a fun puzzle game!
My only suggestion would be to make 'Duplicate' a separate button from 'Pick Up' as having both on the same button is a tad confusing and frustrating.