Magento 2 – Layered Navigation ‘Item with Same ID Already Exists’ Error

Whenever i try to filter by a custom attribute (type = price) i get the error :

Exception #0 (Exception): Item
(Magento\Catalog\Model\Product\Interceptor) with the same ID "871"
already exists

I also have the SQl but im not that familier with SQL code. Can someone see an error here (it is a multisite)

SQL that caused this :SELECT `e`.*, `cat_index`.`position` AS `cat_index_position`, `price_index`.`price`, `price_index`.`tax_class_id`, `price_index`.`final_price`, IF(price_index.tier_price IS NOT NULL, LEAST(price_index.min_price, price_index.tier_price), price_index.min_price) AS `minimal_price`, `price_index`.`min_price`, `price_index`.`max_price`, `price_index`.`tier_price`, `stock_status_index`.`stock_status` AS `is_salable`, IF(at_name.value_id > 0, at_name.value, at_name_default.value) AS `name` FROM `eh_catalog_product_entity` AS `e`  INNER JOIN `eh_catalog_category_product_index` AS `cat_index` ON cat_index.product_id=e.entity_id AND cat_index.store_id=1 AND cat_index.visibility IN(2, 4) AND cat_index.category_id='20'  INNER JOIN `eh_catalog_product_index_price` AS `price_index` ON price_index.entity_id = e.entity_id AND price_index.website_id = '1' AND price_index.customer_group_id = '19'  INNER JOIN `eh_catalog_product_index_eav_decimal` AS `adviced_price_idx` ON adviced_price_idx.entity_id = e.entity_id AND adviced_price_idx.attribute_id = '170' AND adviced_price_idx.store_id
= 1  LEFT JOIN `eh_cataloginventory_stock_status` AS `stock_status_index` ON e.entity_id = stock_status_index.product_id AND stock_status_index.website_id = 0 AND stock_status_index.stock_id
= 1  INNER JOIN `eh_search_tmp_5a1be69bc93529_67461608` AS `search_result` ON e.entity_id = search_result.entity_id  LEFT JOIN `eh_catalog_product_entity_varchar` AS `at_name_default` ON (`at_name_default`.`entity_id` = `e`.`entity_id`) AND (`at_name_default`.`attribute_id` = '73') AND `at_name_default`.`store_id` = 0  LEFT JOIN `eh_catalog_product_entity_varchar` AS `at_name` ON (`at_name`.`entity_id` = `e`.`entity_id`) AND (`at_name`.`attribute_id` = '73') AND (`at_name`.`store_id` = 1) WHERE (adviced_price_idx.value >= 0) AND (adviced_price_idx.value < 10) ORDER BY `name` ASC  LIMIT 9

Anyone any idea?

The problem is caused by duplicate entries in the decimal index table 'product_index_eav_decimal. Does anyone know how this gets generated?

code :

protected function _renderFiltersBefore()
    {
        $this->getCollectionClone();

        $this->getSearchCriteriaBuilder();
        $this->getFilterBuilder();
        $this->getSearch();

        if ($this->queryText) {
            $this->filterBuilder->setField('search_term');
            $this->filterBuilder->setValue($this->queryText);
            $this->searchCriteriaBuilder->addFilter($this->filterBuilder->create());
        }

        $priceRangeCalculation = $this->_scopeConfig->getValue(
            \Magento\Catalog\Model\Layer\Filter\Dynamic\AlgorithmFactory::XML_PATH_RANGE_CALCULATION,
            \Magento\Store\Model\ScopeInterface::SCOPE_STORE
        );
        if ($priceRangeCalculation) {
            $this->filterBuilder->setField('price_dynamic_algorithm');
            $this->filterBuilder->setValue($priceRangeCalculation);
            $this->searchCriteriaBuilder->addFilter($this->filterBuilder->create());
        }

        $searchCriteria = $this->searchCriteriaBuilder->create();
        $searchCriteria->setRequestName($this->searchRequestName);

        try {
            $this->searchResult = $this->getSearch()->search($searchCriteria);
        } catch (\Exception $e) {
            throw new LocalizedException(__('Sorry, something went wrong. You can find out more in the error log.'));
        }

        $temporaryStorage = $this->temporaryStorageFactory->create();
        $table            = $temporaryStorage->storeDocuments($this->searchResult->getItems());

        $this->getSelect()->joinInner(
            [
                'search_result' => $table->getName(),
            ],
            'e.entity_id = search_result.' . TemporaryStorage::FIELD_ENTITY_ID,
            []
        );


        if ($this->order && 'relevance' === $this->order['field']) {
            $this->getSelect()->order('search_result.' . TemporaryStorage::FIELD_SCORE . ' ' . $this->order['dir']);
        }

        parent::_renderFiltersBefore();
    }

This is the result in the database :

Remove one of the 2 child (so its a unique row) and there is no problem anymore