Request.UrlReferrer is not working properly(about latin url)

Hello All,
             I used Request.UrlReferrer to capture the previous URL link, and some paths in URL are portuguese.
     However, I found Request.UrlReferrer recognize(convert) Negócios as Negócios, and Conferências as Conferências 
      Is this about html encoding issue? How to fix it?
      The web system is running on IIS 6, ASP.NET 2.0.
      Thank you.