No you do not need to get an apposite stamp. At the time of the filling, USCIS request copies of any original documents. Any document that is not in English you must provide an English translation of that document done by someone that has no interest in the case (for example it can't be you or your wife), and must be competent in the original language of the document and English. USCIS (or the State Department if an Immigrant Visa is to be issued) will ask to see the original documents later.