Hi All,
I found the solution so,
For the future consideration, different hascode is because of the closed form .cs instance, I added the event listener when the form initializes, but didn't remove the event listener , now when I open the new form then this new form will receive the events two times one for the previous form and one for current form,
So, Whenever you add the eventlistener remove the eventlistener on formCloseBefore Event, using following syntax,
Application.SBO_Application.MenuEvent -= this.MenuEventHandler;