Two canonical URLs

Hello,

On my every page, there are canonical URLs already indicated by default. And the canonical URLs for categories are indicated as: <link href=" www.mysite.com.ua/products/brands/bershka/product/listing " rel="canonical" /> - which is against the structure of my site. I want to change it. How can I do it?

If I put a correct canonical URL into the appropriate field at the category edit page, as result I am getting both canonical URLs in the code of the same page:

<link href=" www.mysite.com.ua/products/brands/bershka/product/listing " rel="canonical" />
and the new one follows below:
<link rel="canonical" href=" www.mysite.com.ua/products/brands/bershka " />

So, how can I remove the first incorrect canonical URL?

-- HikaShop version -- : 2.2.1
-- Joomla version -- : 3.1.1
-- PHP version -- : 5.3.27

Nicolas, thank you!

However, I do not have any special SEF plugin/component/module installed.
Indeed, the first canonical URL was inserted by Joomla's core plugin. So, this seems to be a bug of Joomla.

As a workaround, I have edited file /plugins/system/sef/sef.php by commenting the following lines:

//		if ($uri !== $link)
//		{
//			$doc->addHeadLink(htmlspecialchars($link), 'canonical');
//		}