This is a partial mole that occurs when two sperms fertilize a single ovum.The result is triploidy(69 XXY).Only some of the villi are grape-like,and a fetus can be present,but rarely survives past 15 weeks. This is a partial mole that occurs when two sperms fertilize a single ovum. The result is triploidy (69 XXY). Only some of the villi are grape- like, and a fetus can be present, but rarely survives past 15 weeks