Overwrite block layout inside text_list (content) blocks

I re-developed the whole category page in a layout.xml file included in my custom module, trying to reuse the block names. I needed to change many block (type) classes.

I had read that by redefining the block it overwrote but it is not so. Now the category page works correctly but the block category.products” is printed 3 times.

<catalog_category_default>     <reference name="content">         <block type="ristothemefrontend_handler/catalog_category_view" name="category.categories" template="catalog/category/category-categories.phtml" />         <block type="ristothemefrontend_handler/catalog_category_view" name="category.products" template="catalog/category/view.phtml">             <block type="ristothemefrontend_handler/catalog_product_list" name="product_list" template="catalog/product/list.phtml">                 <action method="setToolbarBlockName"><name>product_list_toolbar</name></action>                 <block type="ristothemefrontend_handler/catalog_product_list_toolbar" name="product_list_toolbar" template="catalog/product/list/toolbar.phtml">                     <block type="page/html_pager" name="product_list_toolbar_pager" />                     <block type="ristothemefrontend_handler/catalog_product_list_toolbar" name="catalog.left" template="catalog/category/left.phtml">                         <block type="ristothemefrontend_handler/catalog_category_view" name="catalog.left.categories" as="categories" template="catalog/category/categories.phtml" />                         <block type="risto_programmablebanners/list" name="catalog.left.banners" as="banners">                             <action method="setBlockType"><type>category</type></action>                         </block>                     </block>                     <block type="ristothemefrontend_handler/catalog_layer_view" name="catalog.left.layer" template="catalog/layer/view.phtml">                         <action method="unsetChild"><alias>category_filter</alias></action>                     </block>                     <block type="ristothemefrontend_handler/catalog_product_list_toolbar" name="category.toolbar" template="catalog/category/toolbar.phtml" />                 </block>                 <block type="ristothemefrontend_handler/catalog_category_view" name="category.products.long_description" template="catalog/category/long_description.phtml"/>             </block>         </block>     </reference> </catalog_category_default> 

The blocks in the previous layouts (base / default etc.) are not overwritten, but loaded.