Basically what D4C's ability means, is that say, Valentine (D4C's stand user) wanted someone to fight for him while say he was injured and needed to recover, he would order his stand to bring out a doppelganger (from a different universe) into his, the doppelganger does NOT have D4C, only the REAL valentine (the one ordering D4C to get a doppelganger) has the stand, D4C's ability makes it so that he can bring other people, not just himself, into a world. One time per say was when he brang a character from part 7 (forgot who) and the Doppelganger of said character and the guy he's duplicating would collide, creating a dice effect.
TL:DR: valentine's D4C can bring people from other dimension/universes into his universe.
