Duvvuri Subbarao may have stepped down as the Reserve Bank of India governor five months ago. But he continues to remain immortal on bank notes.

RBI has printed a set of 2014 currency notes with governor Subbarao's signature. These are largely 500 rupee denominated notes which were printed at the Dewas press in Madhya Pradesh.

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Some concerns were raised about the validity of these notes. But sources from RBI tell CNBC-TV18 that these notes continue to be legal tender and RBI has stopped further production of these 500 rupee notes at Dewas.

This would mean the government will have to bear the cost of replacing the production line with the new template as Dewas press is owned by the government.

However according to RBI sources, this defect was found only at the Dewas press and other printing presses have already changed over to governor Rajan's signature on bank notes.

RBI spokesperson says, "Currency note production is a manufacturing process. Making changes in the process is tedious and takes time in order to keep the disturbance in production to the minimum extent. Changing governor's signature on the banknotes is one such process. To complete the process the banknote presses for all denominations of banknotes is a programme which is under way and is expected to be completed in due course."