UserName keep repeating itself on every event after login

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.NET

Basically after login with valid credentials the username is displayed on the top right corner of the page right before the logOut button but the username keep repeating itself anytime a transaction happens by the way I have the login Control in the masterPage called Root.master. Naturally code behind in Root.master.vb
how can I prevent that from repeating?
Thanks from Guy
--------------------- the .NET------------------------------

 <div class="loginControl"> <dx:ASPxLabel ID="lblUserName"
 runat="server" Text="">
 <dx:ASPxButton ID="btnLogOut"  runat="server" Text="Log Out"
Border-BorderStyle="None">

-------------------the .NET.VB (code Behind)----------------

Public Class Root
    Inherits System.Web.UI.MasterPage

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Session("New") IsNot Nothing Then
            lblUserName.Text += Session("New").ToString()
        Else
            Response.Redirect("wf_Login.aspx")
        End If
    End Sub

    Protected Sub btnLogOut_Click(sender As Object, e As EventArgs)
Handles btnLogOut.Click
        Session("New") = Nothing
        Response.Redirect("wf_Login.aspx")
    End Sub
End Class

[edit]code blocks added[/edit]