You can't use the same name fk_state
for both constraints. Give one of them a different name.
CREATE TABLE IF NOT EXISTS `customers_b` (
`id_customer` INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(45) NOT NULL,
`addr_state` INT NOT NULL,
PRIMARY KEY (`id_customer`),
CONSTRAINT `fk_state_b`
FOREIGN KEY (`addr_state`)
REFERENCES `state` (`id_state`)
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB;