"Dual" (デュアル Dyuaru) is the official term which refers to cards belonging to two different worlds by having two boxes where a world's name is written, one to the left and the other to the right. A dual card's layout characterizes by having the own layout of both worlds divided side by side, while the card name and attribute appear to be centered. Naturally, they work with effects and flags which have one or more specified worlds.

Some cards have three worlds, and are referred to as a "Triple" card.