Double Dildo
There are two types of double Dildos - Let's review both of them!
Double Ended Dildo
The double ended dildos can be used simultaneously by you and your partner. They are usually long enough to be inserted at the same time in both your hole and in your partner hole. They are usually used during lesbian play but can also be used for anal play between male and female. One example of double ended dildo is the "Slim Double Dong" sold by Blush Novelties.
Double penetration dildo
The double penetration dildos typically relate to sextoys that contain two sticks, or two shafts, sharing a same base. They are used by the same person and allow for a combined, dual anal and vaginal penetration. Those sex-toys are often provided with their own suction cups. For example, the King Cock Double Penetrator is a top sale double dildo with integrated suction cup that you can use to fill both holes at the same time.