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This is news to me. Who calls Rahul Gandhi as Rahul Baba ? I havent heard of such a name anywhere - may be in rare cases some people might have called that way.
Yes Sanjay Dutt used to called Sanju baba affectionately by his fans and others. At least Rahul Baba like Sanju baba (though sounds strange) could fit if people make it a nick name - but Baba Rahul sounds totally out of place.