Actually, the Builder has not in a position to supply the said document to all of his customers, as the mother document is only one. If any body wants to take the said document, get a certified document from Sub-registrar office. You can get a zerox copy of the same from your builder.
Once the title was accepted by the bank which offered loan on the development of the property, it means it had scrutinised all the documents including the mother deed. There may a copy of the mother deed with the bankers, based on that copy you may apply and get a certified copy of the same through the registrar office.