Quetz'lun and Hakkar may be of the same race as they share the same model.
Quetz'lun may refer to the Aztec god, Quetzalcoatl, who was called the feathered serpent. Since Quetz'lun looks like a serpent with feathers it is likely that this is the case. Also since Zul'Drak is Aztec styled architecture this could be another clue linking Quetz'lun to the Aztec god. Or it is simply due to the recycling of the Hakkar model.