If you're pregnant at the moment, it's just your subconscious redirecting the thoughts that were going through your head before you went to sleep. You were probably thinking about what the baby is going to be, male or female. Then a sudden thoughts of "Oh God, what if I'm having twins?!?" may have popped in. Even if it was a playful thought, your subconscious took it in.
To dream that you are having twins signifies contrasts and opposites. It also represents contentment, devotion and good business. Lastly it may mean that you are either in an internal battle with yourself or you are in harmony with different people.
Only YOU can determine your own dream and if it was in color in the future Like even the far future you'll be like de ja vu or you'll be like Ohhhh I know what that dream means now and dreams are symbols but as I was saying and dreams that are black and white and nit in color are usually reflections of the past like of your hubby or what you did that day etc.