How do fraternal twins develop from two separate zygotes?

Fraternal twins, also known as dizygotic twins, develop from two separate eggs that are released during the same menstrual cycle and fertilized by two different sperm cells.123

Because each egg is fertilized by a separate sperm, each resulting zygote is genetically unique. Consequently, fraternal twins are no more genetically similar than any other pair of siblings, sharing on average half of their genes, and they may be of the same or different sexes.1423

During development, each zygote typically forms its own chorion (outer sac) and individual placenta, though if the two zygotes implant close together in the uterus, their placentas may fuse and appear as one. This process of multiple ovulation is distinct from monozygotic (identical) twinning, which occurs when a single fertilized egg splits into two separate cell masses.1524