How to avoid duplication problem in seo when create a mobile version of asp.net webpage?

Question

I want to create a mobile version of an existing desktop page. I made copy of my pages and used this code for detecting mobile device :

 public void Page_Load(Object sender, EventArgs e) 
{
    if (Request.Browser["IsMobileDevice"] == "true" ) 
    {
        Response.Redirect(@"~/Content/PageXmobile.aspx");
    }
    else 
    {
        Response.Redirect("PageX.aspx");
    }
}

PageXmobile.aspx is a copy of PageX.aspx except that PageXmobile.aspx is formatted for mobile device but the content is the same on both pages. How to solve this duplication issue?

Answer 1

Be sure to use canonical meta tags or HTTP headers.

Add the following meta tag within both pages and point it to the desktop or primary version:

<link rel="canonical" href="http://www.example.com/article-page" />

You can also send the following HTTP Header along with the request as an alternate way of providing the canonical page:

Link: <http://www.example.com/article-page>; rel="canonical"

Answer 2

If the mobile site is not placed on a subdirectory or if there's no mobile counterpart page (example.com/page1.asp / m.example.com/page1.asp), no need to use the <link rel="canonical" href="https://m.example.com/page1.asp"/>.

If they are separate pages, use the rel="canonical" attribute and don't forget to add mirror or copy the same meta title and description from the main website to the mobile site.