Hi,
It seems that you turned off the option "Append characteristics value to product name" in the configuration. Turning it on displays the product name, the characteristic value and the variant code.
Since you have the size already in the variant code, you see the size twice actually.
It would still be more coherent to have the main product name displayed even when the characteristics value is not appended to the product name. Could you try to turn back off that option and edit the file administrator/components/com_hikashop/classes/product.php and add the code:
if(empty($variant->product_name)){
$variant->product_name = $variant->main_product_name;
}
after the code:
$variant->main_product_name = @$element->product_name;
in that file. Does that display properly ?