Judgments and orders passed by an Appellate Court upon an appeal shall be final, except in the cases provided for in section 418, section 419, sub-section (4) of section 425 or Chapter XXXII: Provided that notwithstanding the final disposal of an appeal against conviction in any case, the Appellate Court may hear and dispose of, on the merits,— (a) an appeal against acquittal under section 419, arising out of the same case; or (b) an appeal for the enhancement of sentence under section 418, arising out of the same case.