1. The loss of original copies can be remedied by obtaining a certified copy from the office of the registrar.
2. While purchasing a new property you should engage a lawyer to carry due diligence which would culminate in the finding on whether the title is free and marketable or not.
3. A property may not be mortgaged but the title of it would still not be clear if there is a dispute pending in relation to it in a court of law, more precisely if a court has ordered stayed on the sale.
4. The seller can also seek to indemnify the purchaser against third party claims by incorporating an indemnity clause in the agreement.