Principal.cs

using System;
using System.Drawing;
using System.Windows.Forms;

namespace R804MoverFigura
{
    public partial class Principal : Form
    {
        public Principal()
        {
            InitializeComponent();
        }

        private bool arrastrandoElipse1 = false;
        private bool arrastrandoElipse2 = false;

        private ElipseControl elipse1;
        private ElipseControl elipse2;

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);

            elipse1 = new ElipseControl();
            elipse1.Width = 100;
            elipse1.Height = 100;
            elipse1.Top = 30;
            elipse1.Left = 30;
            elipse1.BackColor = Color.Red;
            this.Controls.Add(elipse1);

            elipse2 = new ElipseControl();
            elipse2.Width = 100;
            elipse2.Height = 100;
            elipse2.Top = 130;
            elipse2.Left = 130;
            elipse2.BackColor = Color.Azure;
            this.Controls.Add(elipse2);

            elipse1.MouseDown += Elipse_MouseDown;
            elipse1.MouseUp += Elipse_MouseUp;
            elipse1.MouseMove += Elipse_MouseMove;

            elipse2.MouseDown += Elipse_MouseDown;
            elipse2.MouseUp += Elipse_MouseUp;
            elipse2.MouseMove += Elipse_MouseMove;
        }

        private void Elipse_MouseDown(object sender, MouseEventArgs eventArgs)
        {
            Control ctlControl = (Control) sender;

            if(eventArgs.Button == MouseButtons.Left)
            {
                ctlControl.Tag = new Point(eventArgs.X, eventArgs.Y);

                if(ctlControl == elipse1)
                {
                    arrastrandoElipse1 = true;
                }
                else
                {
                    arrastrandoElipse2 = true;
                }
            }
        }

        private void Elipse_MouseUp(object sender, MouseEventArgs eventArgs)
        {
            arrastrandoElipse1 = false;
            arrastrandoElipse2 = false;
        }

        private void Elipse_MouseMove(object sender, MouseEventArgs eventArgs)
        {
            Control ctlControl = (Control) sender;

            if((arrastrandoElipse1 && ctlControl == elipse1) || (arrastrandoElipse2 && ctlControl == elipse2))
            {
                Point punto = (Point) ctlControl.Tag;

                ctlControl.Left = eventArgs.X + ctlControl.Left - punto.X;
                ctlControl.Top = eventArgs.Y + ctlControl.Top - punto.Y;
            }
        }
    }
}