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Well, that wasn't the problem. The problem is your extension. It tries to create a enw block every time you save the config for it.
You have this
$modelo = Mage::getModel('cms/block');
$modelo->setData(array("title"=>"HelloSlide","identifier"=>"helloslide", "content"=>$content, "is_active"=>"1" ,"stores"=>$id_store));
On line 51 of Data.php
You should be looking to see if the block already exists, and if it does, update it instead.