Dual penetrators are designed specifically for anal insertion and simultaneous vaginal penetration.
They are optimized for stimulation of both body parts.
A double penetrator vibe is usually beaded with another rotating or vibrating shaft.
They are created out of soft, pliable pleasure beads that go from large to small, gradually.
They also vibrate, for an intense amount of extra stimulation.
There are also double penetration penis attachments that can be attached just below a man's penis with rings that go around the base of the penis itself and the balls.
These are great dual penetration toys if you really enjoy double penetration but have only one lover on hand.
One end is penis shaped; another is a set of beads; and the third end is smaller for someone who wants to have their first anal intercourse.