code: private EntityType assignUniqueLabel(EntityType entityType, CopyState state) {
      Set<String> existingLabels;
      Package targetPackage = state.targetPackage();
      if (targetPackage != null) {
        existingLabels =
            stream(targetPackage.getEntityTypes()).map(EntityType::getLabel).collect(toSet());
      } else {
        existingLabels =
            dataService
                .query(ENTITY_TYPE_META_DATA, EntityType.class)
                .eq(EntityTypeMetadata.PACKAGE, null)
                .findAll()
                .map(EntityType::getLabel)
                .collect(toSet());
      }
      entityType.setLabel(LabelGenerator.generateUniqueLabel(entityType.getLabel(), existingLabels));
      return entityType;
    }
docs: Checks if there's an EntityType in the target location with the same label. If so, keeps adding
  a postfix until the label is unique.