Pretty interesting to see what organs they have and share:
Abigail and Brittany Hensel - Wikipedia, the free encyclopedia
Common organs
Most of Abigail and Brittany's shared organs lie below the waist line.
2 heads
2 arms -- originally 3, but the short malformed central arm was removed
2 spinal cords and backbones which merge at the pelvis -- surgery corrected scoliosis
3½ lungs -- surgery expanded their chest cavity
2 breasts
2 hearts in a shared circulatory system -- medicine taken by either affects both
1 liver
2 stomachs
3 kidneys
2 gallbladders
1 bladder
1 ribcage
1 large intestine
1 female reproductive system