Unable to install with CiviCRM 4.3.3

[kelson42]

I have CiviCRM 4.3.3 an I'm not able to install the extension with the extension manager.

Feb 02 18:46:13 [info] $Fatal Error Details = Array
(
[callback] => Array
(
[0] => CRM_Core_Error
[1] => handle
)

[code] => -1
[message] => DB Error: unknown error
[mode] => 16
[debug_info] =>         ALTER TABLE civicrm_value_gift_aid_declaration
    ADD COLUMN `post_code` varchar(16),
    ADD INDEX INDEX_post_code ( post_code ) [nativecode=1060 ** Duplicate column name 'post_code']
[type] => DB_Error
[user_info] =>         ALTER TABLE civicrm_value_gift_aid_declaration
    ADD COLUMN `post_code` varchar(16),
    ADD INDEX INDEX_post_code ( post_code ) [nativecode=1060 ** Duplicate column name 'post_code']
[to_string] => [db_error: message="DB Error: unknown error" code=-1 mode=callback callback=CRM_Core_Error::handle prefix="" info="        ALTER TABLE civicrm_value_gift_aid_declaration
    ADD COLUMN `post_code` varchar(16),
    ADD INDEX INDEX_post_code ( post_code ) [nativecode=1060 ** Duplicate column name 'post_code']"]

)

Feb 02 18:46:13 [info] $backTrace = #0 /var/www/donate/modules/civicrm/CRM/Core/Error.php(197): CRM_Core_Error::backtrace("backTrace", TRUE)
#1 internal function: CRM_Core_Error::handle(Object(DB_Error))
#2 /var/www/donate/modules/civicrm/packages/PEAR.php(931): call_user_func((Array:2), Object(DB_Error))
#3 /var/www/donate/modules/civicrm/packages/DB.php(969): PEAR_Error->PEAR_Error("DB Error: unknown error", -1, 16, (Array:2), " ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...") #4 /var/www/donate/modules/civicrm/packages/PEAR.php(564): DB_Error->DB_Error(-1, 16, (Array:2), " ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...")
#5 /var/www/donate/modules/civicrm/packages/DB/common.php(1905): PEAR->raiseError(NULL, -1, NULL, NULL, " ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...", "DB_Error", TRUE) #6 /var/www/donate/modules/civicrm/packages/DB/mysql.php(898): DB_common->raiseError(-1, NULL, NULL, NULL, "1060 *\* Duplicate column name 'post_code'") #7 /var/www/donate/modules/civicrm/packages/DB/mysql.php(327): DB_mysql->mysqlRaiseError() #8 /var/www/donate/modules/civicrm/packages/DB/common.php(1216): DB_mysql->simpleQuery(" ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...")
#9 /var/www/donate/modules/civicrm/packages/DB/DataObject.php(2421): DB_common->query(" ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...") #10 /var/www/donate/modules/civicrm/packages/DB/DataObject.php(1613): DB_DataObject->_query(" ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...")
#11 /var/www/donate/modules/civicrm/CRM/Core/DAO.php(160): DB_DataObject->query(" ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...") #12 /var/www/donate/modules/civicrm/CRM/Core/DAO.php(907): CRM_Core_DAO->query(" ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN p...", FALSE)
#13 /var/www/donate/modules/civicrm/CRM/Core/BAO/SchemaHandler.php(293): CRM_Core_DAO::executeQuery(" ALTER TABLE civicrm_value_gift_aid_declaration\n ADD COLUMN `p...", (Array:0), TRUE, NULL, FALSE, FALSE)
#14 /var/www/donate/modules/civicrm/CRM/Core/BAO/CustomField.php(1870): CRM_Core_BAO_SchemaHandler::alterFieldSQL((Array:6), FALSE, FALSE)
#15 /var/www/donate/modules/civicrm/CRM/Utils/Migrate/Import.php(346): CRM_Core_BAO_CustomField::createField(Object(CRM_Core_DAO_CustomField), "add", FALSE, FALSE)
#16 /var/www/donate/modules/civicrm/CRM/Utils/Migrate/Import.php(78): CRM_Utils_Migrate_Import->customFields(Object(SimpleXMLElement), (Array:2))
#17 /var/www/donate/modules/civicrm/CRM/Utils/Migrate/Import.php(54): CRM_Utils_Migrate_Import->runXmlElement(Object(SimpleXMLElement))
#18 /var/www/donate/sites/default/files/civicrm/extensions/uk.co.compucorp.civicrm.giftaid/civigiftaid.php(32): CRM_Utils_Migrate_Import->run("/var/www/donate/sites/default/files/civicrm/extensions/uk.co.compucorp.civicr...")
#19 /var/www/donate/modules/civicrm/CRM/Extension/Manager/Module.php(64): civigiftaid_civicrm_install()
#20 /var/www/donate/modules/civicrm/CRM/Extension/Manager/Module.php(44): CRM_Extension_Manager_Module->callHook(Object(CRM_Extension_Info), "install")
#21 /var/www/donate/modules/civicrm/CRM/Extension/Manager.php(219): CRM_Extension_Manager_Module->onPreInstall(Object(CRM_Extension_Info))
#22 /var/www/donate/modules/civicrm/CRM/Admin/Form/Extensions.php(188): CRM_Extension_Manager->install((Array:1))
#23 /var/www/donate/modules/civicrm/CRM/Core/Form.php(261): CRM_Admin_Form_Extensions->postProcess()
#24 /var/www/donate/modules/civicrm/CRM/Core/StateMachine.php(160): CRM_Core_Form->mainProcess()
#25 /var/www/donate/modules/civicrm/CRM/Core/QuickForm/Action/Next.php(60): CRM_Core_StateMachine->perform(Object(CRM_Admin_Form_Extensions), "next", "Next")
#26 /var/www/donate/modules/civicrm/packages/HTML/QuickForm/Controller.php(203): CRM_Core_QuickForm_Action_Next->perform(Object(CRM_Admin_Form_Extensions), "next")
#27 /var/www/donate/modules/civicrm/packages/HTML/QuickForm/Page.php(103): HTML_QuickForm_Controller->handle(Object(CRM_Admin_Form_Extensions), "next")
#28 /var/www/donate/modules/civicrm/CRM/Core/Controller.php(345): HTML_QuickForm_Page->handle("next")
#29 /var/www/donate/modules/civicrm/CRM/Core/Page/Basic.php(381): CRM_Core_Controller->run()
#30 /var/www/donate/modules/civicrm/CRM/Core/Page/Basic.php(178): CRM_Core_Page_Basic->edit(1, NULL)
#31 /var/www/donate/modules/civicrm/CRM/Admin/Page/Extensions.php(127): CRM_Core_Page_Basic->run()
#32 /var/www/donate/modules/civicrm/CRM/Core/Invoke.php(323): CRM_Admin_Page_Extensions->run((Array:3), NULL)
#33 /var/www/donate/modules/civicrm/CRM/Core/Invoke.php(72): CRM_Core_Invoke::runItem((Array:13))
#34 /var/www/donate/modules/civicrm/CRM/Core/Invoke.php(52): CRM_Core_Invoke::_invoke((Array:3))
#35 /var/www/donate/modules/civicrm/drupal/civicrm.module(456): CRM_Core_Invoke::invoke((Array:3))
#36 internal function: civicrm_invoke("admin", "extensions")
#37 /var/www/donate/includes/menu.inc(517): call_user_func_array("civicrm_invoke", (Array:2))
#38 /var/www/donate/index.php(21): menu_execute_active_handler()
#39 {main}

If I delete the table "civicrm_value_gift_aid_declaration", the installer complains that the table does not exist.