public class MyEventer
    {
        public readonly Guid GUID = Guid.NewGuid();
        public class MyArgs : EventArgs
        {
            public Guid GUID { get; set; }
            public string Message { get; set; }
        }
        private event EventHandler<MyArgs> MyEvent;

        public MyEventer()
        {
            MyEvent += MyEventer_MyEvent;
        }

        void MyEventer_MyEvent(object sender, MyEventer.MyArgs e)
        {
            if (e.GUID == GUID)
                return;
            //обработка
        }
        public void OnEvent(string message)
        {
            var e = MyEvent;
            if (e != null)
            {
                e(null, new MyArgs() { GUID = this.GUID, Message = message });
            }
        }
    }