Dear Mr. Pradip,
First of all congratulations for your new house!
While executing property documents, there are chances that some mistakes may occur. This can happen in the process of execution of the documents. It is always advisable to get these mistakes rectified at the earliest; otherwise there may be chances of defect in title at a later stage. The errors may relate to the name of the parties, their address, area of the property, dimension, location, survey number of the property, or the consideration amount. You may check all other property documents like, the Allotment Letter/Booking Letter, Agreement to Sale, Receipts etc. and if in all the documents, correct property details are mentioned, this mistake may be ignored. However, it is always advisable to get a Rectification Deed.
There can be typing errors which can be rectified by the execution of a supplementary document called correction deed or rectification deed. In your case, it seems that only at one place, there is a mistake since, the Sub-Registrar has issued Index-II reflecting correct details of property, and it also seems that the at other places in the Sale Deed including the Schedule of property, correct property details are mentioned.
It is to be noted here that there must have been a bona fide mistake where the original deed does not reflect the true intention of parties to the deed in question. The parties to the agreement must concur on modifying the original agreement by addition, deletion, or rectification of any terms referred to in the already executed deed. The parties need to get the corrections into a duly executed document. Further, they need to pay the requisite stamp duty in order to get it registered with the concerned registering authority.
A correction deed should be executed after mutual consent of all the parties to the main deed. All parties to the original deed should jointly execute the rectification deed as well. In case the original deed has been registered, one should get the rectification deed also registered, and pay the requisite stamp duty and registration charges as per the laws in force in the State concerned.
Please note that no party to the deed can make any changes to the document after it is registered which will not be legal. Since, the builder himself did the correction on the original Sale Agreement and counter signed it, it will have not value since, the correction does not bear the seal of the registrar that is to say it needs to be evinced by the concerned registrar.
As far as the issue with the Financial Institution is concerned, you may check the Loan Agreement and check the details of the property mortgaged. If it is brought to the notice of the Financial Institution, it will insist on the Rectification Deed or else, it may ask for a written letter from the Builder counter-signed by you regarding the typographic mistake in Sale Deed.
Hope you have found the above information useful.