Validity of True/Certified Copy

Sure, a certified copy of a document obtained from the respective Registrar office is similar to that of its Original and acceptable every where. Afterall it is prepared from the document which is registered at the Registrar Office. So there is no doubt, if it is procured through process.

True copy is not sufficient to sell the property. If the original will traced out, you [the vendor] may create antoher document in third party's name. Before the selling or registering the property in the name of vendee, you may lodge a complaint before concerned police station and obtain a certificate from the concerned S.H.O. of police station and narate all the facts in an affidavit before notary-advocate, indemnifying that if the original traced out that will be handedover to the vendee. There after the said certificate and affidavit which attested by notary shall be annexed to the sale deed through which you are selling the property and handover the same to the vendee. 

But for the purpose of sell of property, a copy of the original deed is not required. What is required is mutual trust. further, it is the vendee who should be concerned, not the vendor.

Certain documents like one maintined in registrar office PUBLIC DOCUMENTS and they are able to proove the fact that one original of the kind copy issued does exist.But in a transaction  of sale neither the orriginal nor its certified copy is required for any proceedural matter of sale. But it is bounden duty of buyer(called also vendee) that he satisfies himself about the title of seller(called also vendor)to fare and free of all charges and encumberences for buyer should 30yearsregistry record and should also callfor the original title deed from seller because there may be some equitable mortgaeby simply of deposit  the original saledeed. hence best course is to ask the seller to report to police via fir about the loss togather with a recital of loss and its report by fir and also a specific covenant or term clause whereby seller undertakes to indemnify buyer if subsequently any title defect arises of any nature in the title of seller consideration togather with a rate of interest fixed in deed shall be payble from the date of deed.