protected function isExistingRow($row, $attribute)
    {
        $rowAttributes = $row;
        unset($rowAttributes[$this->relationalData[$attribute]['junctionColumn']]);

        foreach ($this->relationalData[$attribute]['oldRows'] as $oldRow) {
            $oldModelAttributes = $oldRow;
            unset($oldModelAttributes[$this->relationalData[$attribute]['junctionColumn']]);
            if ($oldModelAttributes == $rowAttributes) {
                return true;
            }
        }

        return false;
    }