You cannot define a correlation name 'oxygen_output_idx' more than once

#0 /var/www/upettools.com/lib/Varien/Db/Select.php(281): Zend_Db_Select->_join('inner join', Array, 'oxygen_output_i...', Array, NULL)
#1 /var/www/upettools.com/lib/Zend/Db/Select.php(336): Varien_Db_Select->_join('inner join', Array, 'oxygen_output_i...', Array, NULL)
#2 /var/www/upettools.com/lib/Zend/Db/Select.php(315): Zend_Db_Select->joinInner(Array, 'oxygen_output_i...', Array, NULL)
#3 /var/www/upettools.com/app/code/core/Mage/Catalog/Model/Resource/Layer/Filter/Attribute.php(70): Zend_Db_Select->join(Array, 'oxygen_output_i...', Array)
#4 /var/www/upettools.com/app/code/core/Mage/Catalog/Model/Layer/Filter/Attribute.php(94): Mage_Catalog_Model_Resource_Layer_Filter_Attribute->applyFilterToCollection(Object(Mage_Catalog_Model_Layer_Filter_Attribute), '115')
#5 /var/www/upettools.com/app/code/core/Mage/Catalog/Block/Layer/Filter/Abstract.php(91): Mage_Catalog_Model_Layer_Filter_Attribute->apply(Object(Mage_Core_Controller_Request_Http), Object(Mage_Catalog_Block_Layer_Filter_Attribute))
#6 /var/www/upettools.com/app/code/core/Mage/Catalog/Block/Layer/Filter/Abstract.php(73): Mage_Catalog_Block_Layer_Filter_Abstract->_initFilter()
#7 /var/www/upettools.com/app/code/core/Mage/Catalog/Block/Layer/View.php(136): Mage_Catalog_Block_Layer_Filter_Abstract->init()
#8 /var/www/upettools.com/app/code/core/Mage/Core/Block/Abstract.php(293): Mage_Catalog_Block_Layer_View->_prepareLayout()
#9 /var/www/upettools.com/app/code/core/Mage/Core/Model/Layout.php(456): Mage_Core_Block_Abstract->setLayout(Object(Mage_Core_Model_Layout))
#10 /var/www/upettools.com/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout->createBlock('catalog/layer_v...', 'catalog.leftnav')
#11 /var/www/upettools.com/app/code/core/Mage/Core/Model/Layout.php(239): Mage_Core_Model_Layout->addBlock('catalog/layer_v...', 'catalog.leftnav')
#12 /var/www/upettools.com/app/code/core/Mage/Core/Model/Layout.php(205): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element))
#13 /var/www/upettools.com/app/code/core/Mage/Core/Model/Layout.php(210): Mage_Core_Model_Layout->generateBlocks(Object(Mage_Core_Model_Layout_Element))
#14 /var/www/upettools.com/app/code/core/Mage/Core/Controller/Varien/Action.php(344): Mage_Core_Model_Layout->generateBlocks()
#15 /var/www/upettools.com/app/code/core/Mage/Catalog/controllers/CategoryController.php(148): Mage_Core_Controller_Varien_Action->generateLayoutBlocks()
#16 /var/www/upettools.com/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Catalog_CategoryController->viewAction()
#17 /var/www/upettools.com/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('view')
#18 /var/www/upettools.com/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#19 /var/www/upettools.com/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#20 /var/www/upettools.com/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#21 /var/www/upettools.com/index.php(111): Mage::run('', 'store')
#22 {main}