One of our units has developed moisture inside the two panes (seal has gone obviously)----when a new unit is installed do the 2 old pieces of glass get used again to make another unit?----if so why should we be charged for complete new glass?
If you mean - used again for YOUR unit - then, you'd have a big hole while waiting for the unit to be made.
If you mean - used again for ANY other person's unit - then, no...because these things are made-to-measure and are all different, and may not be used. That's apart from breakages and labour costs...