[Solved] Duplicate (double) record inserted in database in ASP.Net

I checked my code and I don’t what I might be missing but it looks okay.

However, it is still inserting double data into table.

Here is my full code of the web form, Please help me and check if I had missed something that I don’t know. Thank you

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        protected void buttonmail_Click(object sender, EventArgs e)
        {
            string filename = Path.GetFileName(showPreviewBill.PostedFile.FileName);
            string contentType = showPreviewBill.PostedFile.ContentType;
            using (Stream fs = showPreviewBill.PostedFile.InputStream)
            {
                using (BinaryReader br = new BinaryReader(fs))
                {
                    byte[] bytes = br.ReadBytes((Int32)fs.Length);
                    using (SqlConnection con = new SqlConnection("Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\Dataregister.mdf;Integrated Security=True"))
                    {
                        string query = "INSERT INTO tableinvoice(email, Name, ContentType, Data, Uid, CreatedBy, Role, CreatedDate, Organization)" +
                    " VALUES(@email, @Name, @ContentType, @Data, @Uid, @CreatedBy, @Role, @CreatedDate, @Organization); SELECT @@IDENTITY";
                        using (SqlCommand cmd = new SqlCommand(query))
                        {
                            cmd.Connection = con;
                            cmd.Parameters.AddWithValue("@email", user.Text.Trim());
                            cmd.Parameters.AddWithValue("@Name", filename);
                            cmd.Parameters.AddWithValue("@ContentType", contentType);
                            cmd.Parameters.AddWithValue("@Data", bytes);
                            cmd.Parameters.AddWithValue("@Uid", labelid.Text.Trim());
                            cmd.Parameters.AddWithValue("@CreatedBy", createby.Text.Trim());
                            cmd.Parameters.AddWithValue("@Role", role.Text.Trim());
                            cmd.Parameters.AddWithValue("@CreatedDate", DateTime.Now);
                            cmd.Parameters.AddWithValue("@Organization", named.Text.Trim());
                            con.Open();
                            cmd.ExecuteNonQuery();
                            object Invoice = cmd.ExecuteScalar();
                            con.Close();
                            Session["paperinv"] = Invoice;
                            Response.Redirect("Invoiceprint.aspx");
                        }
                    }
                }
            }