Security :: Can CreateUserWizard With Creating Dupicate User While Assigning Role

protected void CreateUserWizard1_CreatedUser(object sender, EventArgs e)
{
Roles.AddUserToRole((sender as CreateUserWizard).UserName, "Customers");
}

CreateUserWizard is creating dupicate user while assigning Role.How can we assign Role without duplicating user record? I've observed ApplicationID for assigning Role is Differenent than Creating New User, so when ever Role assigning comes in, it creates same user again with new UserID. Is it related to Web.Config in some way? As when I try to create user from "VisualStudio/Website/ASP.net Configuration"