1. Sweet Valley High - (the most famous twins of all times is Jessica and Elizabeth Wakefield ^_^) The story revolved around the lives of teenagers Jessica and Elizabeth Wakefield, twins who live in Sweet Valley, California. The series quickly gained popularity and spawned several spin-off series. The books are generally classified as young-adult or kids' fiction.
2. Baby Sitters Club - The series is about a group of middle school students living in the fictional town of Stoneybrook, Connecticut. They run a business called the Baby-sitters Club that helps parents find babysitters from the club available for jobs by calling during their club meetings. Meetings take place Monday, Wednesday, and Friday from 5:30 p.m. to 6:00 p.m. The club runs financially on dues and fundraising, and the babysitters write diaries of their jobs to help each other. The members of the club are also best friends, although they go through many conflicts throughout the series.
The club starts out with four members (Kristy Thomas, Mary Anne Spier, Claudia Kishi, and Stacey McGill), eventually expanding to ten. All of the main characters are thirteen, with the exception of junior members Mallory Pike and Jessica Ramsey, who are two years younger.
3. Hardy Boys - The Hardy Boys are fictional teenage brothers and amateur detectives. They live in the town of Bayport with their father, detective Fenton Hardy, their mother, Laura Hardy, and their Aunt Gertrude. Frank, the elder brother, is 18 , and his younger brother Joe is 17. The brothers nominally attend high school in Bayport, where they are in the same grade, but school is rarely mentioned in the books and never hinders the Hardy's in solving mysteries
4. Bobbsey Twins- The books related the adventures of the children of the middle-class Bobbsey family, which included two sets of fraternal twins: Bert and Nan, who were 12 years old, and Flossie and Freddie, who were six.
Ha! Loved stories about twins! I am always fascinated with the adventures of all the twins that I've read :D made me wish that I should have been born with a twin sister or brother :D must have been nice to have a twin ^^ all the adventure that I could have had! pulling pranks by pretending your twin and have someone to switch class to when you're bores out of your wits!
Reminiscing all of this books that I used to read made me want to find them on our bodega :D