BackgroundWorker's RunWorkerCompleted запускается дважды

Я создал небольшой проект с индикатором выполнения, чтобы проверить, как BackgroundWorker выполняет свою работу. Таким образом, индикатор выполнения работает от 0 до 100%. Но теперь то, что я хочу сделать, это запустить еще один BackgroundWorker после того, как первый закончит свою работу. Второй BackgroundWorker просто должен отображать MessageBox. Я положил второе RunWorkerAsync() событие RunWorkerAsync() в конце первого рабочего RunWorkerCompleted(). Чтобы убедиться, что первый рабочий метод завершен. Странная вещь, которая случается, заключается в том, что мое второе DoWork() событие срабатывает дважды. Это упрощенная версия ошибки, которую я получаю в своей основной программе. Может ли кто-нибудь определить проблему?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace backgroundworker
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            bw1 = new BackgroundWorker();
            bw1.DoWork += new DoWorkEventHandler(bw1_DoWork);
            bw1.ProgressChanged += new ProgressChangedEventHandler(bw1_ProgressChanged);
            bw1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw1_RunWorkerCompleted);
            bw1.WorkerReportsProgress = true;
            bw1.WorkerSupportsCancellation = true;
            bw2.DoWork += new DoWorkEventHandler(bw2_DoWork);
            bw2.ProgressChanged += new ProgressChangedEventHandler(bw2_ProgressChanged);
            bw2.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw2_RunWorkerCompleted);
        }

        private void bw1_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 0; i < 100; i++)
            {
                Thread.Sleep(50);                   
                bw1.ReportProgress(i);
                if (bw1.CancellationPending)
                {
                    e.Cancel = true;
                    bw1.ReportProgress(0);
                    return;
                }
            }
            bw1.ReportProgress(100);
        }

        private void bw1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        { 
            progressBar1.Value = e.ProgressPercentage;
            lblStatus.Text = "Processing......" + progressBar1.Value.ToString() + "%";
        }

        private void bw1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                lblStatus.Text = "Task Cancelled.";
            }

            else if (e.Error != null)
            {
                lblStatus.Text = "Error while performing background operation.";
            }
            else
            {
                lblStatus.Text = "Task Completed...";
            }

            btnStartAsyncOperation.Enabled = true;
            btnCancel.Enabled = false;
            bw2.RunWorkerAsync();   
        }

        private void btnStartAsyncOperation_Click(object sender, EventArgs e)
        {
            btnStartAsyncOperation.Enabled = false;
            btnCancel.Enabled = true;    
            bw1.RunWorkerAsync();                    
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            if (bw1.IsBusy)
            {
                bw1.CancelAsync();
            }
        }

        private void bw2_DoWork(object sender, DoWorkEventArgs e)
        {
        }

        private void bw2_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {

        }

        private void bw2_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
             MessageBox.Show("Second task is done too.");
        }
    }
}

Обновление: Form1.Designer.cs

namespace backgroundworker
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.progressBar1 = new System.Windows.Forms.ProgressBar();
            this.lblStatus = new System.Windows.Forms.Label();
            this.bw1 = new System.ComponentModel.BackgroundWorker();
            this.btnStartAsyncOperation = new System.Windows.Forms.Button();
            this.btnCancel = new System.Windows.Forms.Button();
            this.bw2 = new System.ComponentModel.BackgroundWorker();
            this.SuspendLayout();
            // 
            // progressBar1
            // 
            this.progressBar1.Location = new System.Drawing.Point(12, 154);
            this.progressBar1.Name = "progressBar1";
            this.progressBar1.Size = new System.Drawing.Size(1164, 100);
            this.progressBar1.TabIndex = 1;
            // 
            // lblStatus
            // 
            this.lblStatus.AutoSize = true;
            this.lblStatus.Font = new System.Drawing.Font("Microsoft Sans Serif", 15.75F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
            this.lblStatus.Location = new System.Drawing.Point(469, 42);
            this.lblStatus.Name = "lblStatus";
            this.lblStatus.Size = new System.Drawing.Size(70, 25);
            this.lblStatus.TabIndex = 2;
            this.lblStatus.Text = "label1";
            // 
            // bw1
            // 
            this.bw1.WorkerReportsProgress = true;
            this.bw1.WorkerSupportsCancellation = true;
            this.bw1.DoWork += new System.ComponentModel.DoWorkEventHandler(this.bw1_DoWork);
            this.bw1.ProgressChanged += new System.ComponentModel.ProgressChangedEventHandler(this.bw1_ProgressChanged);
            this.bw1.RunWorkerCompleted += new System.ComponentModel.RunWorkerCompletedEventHandler(this.bw1_RunWorkerCompleted);
            // 
            // btnStartAsyncOperation
            // 
            this.btnStartAsyncOperation.Location = new System.Drawing.Point(12, 109);
            this.btnStartAsyncOperation.Name = "btnStartAsyncOperation";
            this.btnStartAsyncOperation.Size = new System.Drawing.Size(160, 39);
            this.btnStartAsyncOperation.TabIndex = 3;
            this.btnStartAsyncOperation.Text = "Start";
            this.btnStartAsyncOperation.UseVisualStyleBackColor = true;
            this.btnStartAsyncOperation.Click += new System.EventHandler(this.btnStartAsyncOperation_Click);
            // 
            // btnCancel
            // 
            this.btnCancel.Location = new System.Drawing.Point(1024, 109);
            this.btnCancel.Name = "btnCancel";
            this.btnCancel.Size = new System.Drawing.Size(152, 39);
            this.btnCancel.TabIndex = 4;
            this.btnCancel.Text = "Cancel";
            this.btnCancel.UseVisualStyleBackColor = true;
            this.btnCancel.Click += new System.EventHandler(this.btnCancel_Click);
            // 
            // bw2
            // 
            this.bw2.DoWork += new System.ComponentModel.DoWorkEventHandler(this.bw2_DoWork);
            this.bw2.ProgressChanged += new System.ComponentModel.ProgressChangedEventHandler(this.bw2_ProgressChanged);
            this.bw2.RunWorkerCompleted += new System.ComponentModel.RunWorkerCompletedEventHandler(this.bw2_RunWorkerCompleted);
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(1188, 272);
            this.Controls.Add(this.btnCancel);
            this.Controls.Add(this.btnStartAsyncOperation);
            this.Controls.Add(this.lblStatus);
            this.Controls.Add(this.progressBar1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.ProgressBar progressBar1;
        private System.Windows.Forms.Label lblStatus;
        private System.ComponentModel.BackgroundWorker bw1;
        private System.Windows.Forms.Button btnStartAsyncOperation;
        private System.Windows.Forms.Button btnCancel;
        private System.ComponentModel.BackgroundWorker bw2;
    }
}