Avoid multiple windows of the same kind

[Gribouillis]

You can add a boolean to remember if the window was already created

def on_press(event):
    if on_press.window_created:
        return
    cont,att = rect[0].contains(event)
    if cont == True:
        win = tk.Tk()
        on_press.window_created = True
        label1 = ttk.Label(win, text ="Test1").grid(column=0,row=0)
        label2 = ttk.Label(win, text ="Test2").grid(column=0,row=1)
        label3 = ttk.Label(win, text ="Test3").grid(column=0,row=2)
on_press.window_created = False
...