Christmas Bells is one of my favorite Primary Christmas songs. The arrangement is my only published duet, and is fairly simple for two people to play at an intermediate level. The pianists are meant to create a sort of echo like a bell ringing off of each other. A more challenging approach would be to play as much of the duet as you can by yourself, taking whatever parts you like best from each.
This song is also available in the full piano book for "Softly Christmas" available here.