Hi,
i manage an italian website and we started translating it few months ago.

I have a lot of articles that are only in italian and not translated in english... when i look inside the SEF url manager in sh404sef (i bought your plugin) i see that those article have both an italian sef url and an english sef url generated with the same alias (having the en/ prefix before the alias and using the english language in the K2 non-sef url).
I spoke a lot with sh404sef team and they prompt me here.
I took trace of the generation of that url and here are the results:

The url is this:
www.lifeintravel.it/en/visitare-la-liguria-10-cose-da-vedere-per-innamorarsi-della-regione.html

and inside the details i have:

source (Sef)
/en/visitare-la-liguria-10-cose-da-vedere-per-innamorarsi-della-regione.html

and
Source URL (Non-SEF) index.php?option=com_k2&Itemid=4088&id=4293&lang=en&view=itemTrace
#0 /home2/zwlifein/public_html/administrator/components/com_sh404sef/classes/router.php(1036): Sh404sefHelperUrl::storeUrlSource()
#1 [internal function]: Sh404sefClassRouterInternal->buildRule(Object(Joomla\CMS\Router\SiteRouter), Object(Joomla\CMS\Uri\Uri))
#2 /home2/zwlifein/public_html/libraries/src/Router/Router.php(638): call_user_func_array(Array, Array)
#3 /home2/zwlifein/public_html/libraries/src/Router/SiteRouter.php(657): Joomla\CMS\Router\Router->processBuildRules(Object(Joomla\CMS\Uri\Uri), '')
#4 /home2/zwlifein/public_html/libraries/src/Router/Router.php(614): Joomla\CMS\Router\SiteRouter->processBuildRules(Object(Joomla\CMS\Uri\Uri))
#5 /home2/zwlifein/public_html/libraries/src/Router/Router.php(270): Joomla\CMS\Router\Router->_processBuildRules(Object(Joomla\CMS\Uri\Uri))
#6 /home2/zwlifein/public_html/libraries/src/Router/SiteRouter.php(154): Joomla\CMS\Router\Router->build('index.php?optio...')
#7 /home2/zwlifein/public_html/libraries/src/Router/Route.php(144): Joomla\CMS\Router\SiteRouter->build('index.php?optio...')
#8 /home2/zwlifein/public_html/libraries/src/Router/Route.php(93): Joomla\CMS\Router\Route::link('site', 'index.php?optio...', true, 0, false)
#9 /home2/zwlifein/public_html/plugins/sh404sefcore/sh404sefsimilarurls/sh404sefsimilarurls.php(314): Joomla\CMS\Router\Route::_('index.php?optio...')
#10 /home2/zwlifein/public_html/plugins/sh404sefcore/sh404sefsimilarurls/sh404sefsimilarurls.php(115): shFormatSimilarUrls(Array)
#11 /home2/zwlifein/public_html/plugins/sh404sefcore/sh404sefsimilarurls/sh404sefsimilarurls.php(72): shGetSimilarUrls('/en/visitare-la...', Object(Joomla\Registry\Registry))
#12 /home2/zwlifein/public_html/libraries/joomla/event/dispatcher.php(165): plgSh404sefsimilarurls('com_content.arc...', Object(stdClass), Object(Joomla\Registry\Registry), 0)
#13 /home2/zwlifein/public_html/components/com_sh404sef/views/error404/view.html.php(54): JEventDispatcher->trigger('oncontentprepar...', Array)
#14 /home2/zwlifein/public_html/libraries/src/MVC/Controller/BaseController.php(672): Sh404sefViewError404->display()
#15 /home2/zwlifein/public_html/libraries/src/MVC/Controller/BaseController.php(710): Joomla\CMS\MVC\Controller\BaseController->display()
#16 /home2/zwlifein/public_html/administrator/components/com_sh404sef/helpers/error.php(266): Joomla\CMS\MVC\Controller\BaseController->execute('')
#17 /home2/zwlifein/public_html/administrator/components/com_sh404sef/helpers/error.php(85): Sh404sefHelperError::render(Object(JException), 'The page you re...')
#18 /home2/zwlifein/public_html/administrator/components/com_sh404sef/classes/router.php(2210): Sh404sefHelperError::render404ErrorDocument(Object(JException))
#19 /home2/zwlifein/public_html/libraries/legacy/error/error.php(780): Sh404sefClassRouterInternal->sh404sefErrorPage(Object(JException))
#20 /home2/zwlifein/public_html/libraries/legacy/error/error.php(241): JError::handleCallback(Object(JException), Array)
#21 /home2/zwlifein/public_html/libraries/legacy/error/error.php(202): JError::throwError(Object(JException))
#22 /home2/zwlifein/public_html/libraries/legacy/error/error.php(277): JError::raise(1, 404, 'Item not found', NULL, true)
#23 /home2/zwlifein/public_html/components/com_k2/views/item/view.html.php(55): JError::raiseError(404, 'Item not found')
#24 /home2/zwlifein/public_html/libraries/src/MVC/Controller/BaseController.php(672): K2ViewItem->display()
#25 /home2/zwlifein/public_html/components/com_k2/controllers/controller.php(19): Joomla\CMS\MVC\Controller\BaseController->display(false, Array)
#26 /home2/zwlifein/public_html/components/com_k2/controllers/item.php(78): K2Controller->display(false, Array)
#27 /home2/zwlifein/public_html/libraries/src/MVC/Controller/BaseController.php(710): K2ControllerItem->display()
#28 /home2/zwlifein/public_html/components/com_k2/k2.php(64): Joomla\CMS\MVC\Controller\BaseController->execute('')
#29 /home2/zwlifein/public_html/libraries/src/Component/ComponentHelper.php(402): require_once('/home2/zwlifein...')
#30 /home2/zwlifein/public_html/libraries/src/Component/ComponentHelper.php(377): Joomla\CMS\Component\ComponentHelper::executeComponent('/home2/zwlifein...')
#31 /home2/zwlifein/public_html/libraries/src/Application/SiteApplication.php(194): Joomla\CMS\Component\ComponentHelper::renderComponent('com_k2')
#32 /home2/zwlifein/public_html/libraries/src/Application/SiteApplication.php(233): Joomla\CMS\Application\SiteApplication->dispatch()
#33 /home2/zwlifein/public_html/libraries/src/Application/CMSApplication.php(196): Joomla\CMS\Application\SiteApplication->doExecute()
#34 /home2/zwlifein/public_html/index.php(49): Joomla\CMS\Application\CMSApplication->execute()
#35 {main}

It seems that the source is this:
index.php?option=com_k2&Itemid=4088&id=4293&lang=en&view=itemTrace
but i don't know what itemTrace is?

Is there a way to avoid having that sef url generated?

Thanks a lot for your answer and your great component.

PS: sorry for my bad english

Thanks Fotis for your answer.
It leads to 404 because that article is in Italian but still K2 generates an english version of that article.
My problem is that all the articles that i create in italian have an english version (non-sef K2 url) that generate url in sh404sef that have english prefix and lead to 404.
Is it normal that if i assign one language (italian) to an article, K2 still generates the other language (english) url?
It shouldn't... or am i wrong?
Thanks

I have no access to the help desk because I actually don't have an active subscription (it is expired) to the plugin.