Question: who is the best selling duo of all time
[{'answer': 'Hall and Oates', 'provenance': [{'wikipedia_id': '175028', 'title': 'Hall & Oates', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '175028', 'title': 'Hall & Oates', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 878, 'bleu_score': 0.9086095243711421, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3237008911316532334}, 'section': 'Section::::Abstract.'}]}]