One of my family room's window glass has been broken. The window is vinyl window with two layers of glasses. The inner side (room side) glass is broken while the outer side glass is intact. I have contacted couple of local contractors over phone, they told me I have to replace both glasses (inner and outer) because it is "thermal window glass" with two layers of glasses. My question is: 1) Should I really replace both layers of glasses of the window ? 2) Can anyone give be an estimate of cost for replacement ? (I am in Ottawa, Canada, window size: 6 feet by 2 feet (glass size: 5 feet by 1.5 feet) Thanks.