def MaintainUniqueness(df_dc, df_marvel):
    """ Maintain uniqueness by creating new ids and source column """
    df_dc["NEW_PAGEID"] = df_dc["PAGE_ID"].apply(lambda id: str(id)+"_dc")
    df_marvel["NEW_PAGEID"] = df_marvel["PAGE_ID"].apply(lambda id: str(id)+"_marvel")
    df_dc["COMICS"] = "DC"
    df_marvel["COMICS"] = "Marvel"
    return df_dc, df_marvel