double dominoRegal Games Mexican Train Double 12 Dominoes Set for Adults & Kids - Domino Game with 91 Tiles Colored Dots & 4 Metal Trains - 2-8 Player Games & Ideal for Family Fun Game Nht and TravelA double-12 domino. A double is any tile with identical pips on both sides. Using a quarter or penny is a great way to mark an open train or station. Each player’s first move & opening private trains