A common trope in sci fi are alien species that either look exactly like humans or very close to humans. Look at Krypton from the Superman franchise or a third of the aliens in Star Trek.
Science Fiction has been used as allegory for social commentary and exploration of race relations and bigotry have not been exempt. However when these issues are discussed, racism is usually portrayed between two different species such as the Cardassians and Bajorans from Deep Space Nine rather than on the basis of ethnicity.
This makes sense. When trying to address real world issues using science fiction, you usually want to portray the subject matter in a more fantastical manner than you would otherwise. Still, I think it's a missed opportunity.