From a biological point of view, the differences in these fraternal or dizygotic twins from two biracial parents are not surprising.
The parents of such twins, who are typically both of mixed race, have a combination of alleles for light and dark skin in their genome.
Each sperm or egg cell possesses a random selection of genes from its mother or father.
In such cases, fraternal twins can differ from each other quite dramatically in terms of skin color or other physical characteristics.
In the 1970s reboot of Wonder Woman, the white-skinned Diana has a black-skinned twin sister named Nubia, who was kidnapped at birth by Ares and is historically DC Comics' first black superheroine.