Following the reissue of The Baby-Sitter's Club they have come out with the the Sweet Valley Twins series in graphic novel format.
This series features identical twins Jessica and Elizabeth Wakefield as they navigate 6th grade and their developing individual styles and personalities.
This series was very prolific in the late 80's/90's and the core of the story and characters is still very present. The story has clearly been updated though and brought into the present with current technology and a more diverse representation of characters. The first volume of this series is recommended for readers 8-12 and a second volume of the series will be out in June.