S.W.
Wow twins with their own day - yeah. They make act alike but they have something very special. You could alternate in coming years which day you celebrate or have it on a weekend for both. They may change what they like and who the like and it may mean separate parties but until then just enjoy them as they are. They don't really care right now about what day as long as they have a party and friends.
Enjoy the time with them and enjoy the holidays.
The other S.