Python test cases seem to contradict themselves on duplcation. The simple test cases say we shouldn't allow duplications, ex:

[['cheese'], ['rat', 'rat', 'tar'], ['star', 'tars', 'tsar']] should equal [['cheese'], ['rat', 'tar'], ['star', 'tars', 'tsar']]

while the random tests allow lots of duplication, see the ['Mm', 'mM'] failure below

[['AQipcR', 'ARciQp', 'ARicQp', 'AipcQR', 'ApcQiR', 'QcApiR', 'QpAcRi', 'QpiRcA', 'RQpAic', 'RcApiQ', 'RpiQAc', 'cARiQp', 'cRpQAi', 'pRAciQ'], ['BpUDwoj', 'BpUowjD', 'BwUDopj', 'DoBwjUp', 'DpwUjoB', 'DwoBpjU', 'UpjwoDB', 'UwjopBD', 'jBUwDop', 'oUwDjBp', 'opBjUwD', 'opjUBDw', 'pUjwoBD', 'pjDBoUw', 'pjowUDB', 'poBUjwD', 'wUBjoDp', 'wUjBDpo'], ['BwUDopj', 'DUpBwoj', 'pUjwoBD'], ['CiboySMp', 'MoCpibSy', 'MpSboiCy', 'bCMyiopS', 'ipboySCM', 'oCiSpybM', 'oiMbSpCy', 'oypbCiSM', 'pCMyiobS', 'yiCpoMbS', 'yoCMSibp', 'ypCSbMio'], ['FPcusOuzT', 'FPsOuzTcu', 'FczuTusPO', 'OuPucFszT', 'OuuczFTsP', 'PFOuzucsT', 'PuTFucOzs', 'cFOTPuzsu', 'cTuzuPOFs', 'csuuzTFPO', 'sFuPzuTOc', 'uPOFTczsu', 'uzuFOPcTs', 'zOcFsTuPu', 'zcsPuFOuT'], ['Mm', 'mM']]

should equal

[['AQipcR', 'ARciQp', 'ARicQp', 'AipcQR', 'ApcQiR', 'QcApiR', 'QpAcRi', 'QpiRcA', 'RQpAic', 'RcApiQ', 'RpiQAc', 'cARiQp', 'cRpQAi', 'pRAciQ'], ['BpUDwoj', 'BpUowjD', 'BwUDopj', 'DUpBwoj', 'DoBwjUp', 'DpwUjoB', 'DwoBpjU', 'UpjwoDB', 'UwjopBD', 'jBUwDop', 'oUwDjBp', 'opBjUwD', 'opjUBDw', 'pUjwoBD', 'pjDBoUw', 'pjowUDB', 'poBUjwD', 'wUBjoDp', 'wUjBDpo'], ['CiboySMp', 'MoCpibSy', 'MpSboiCy', 'bCMyiopS', 'ipboySCM', 'oCiSpybM', 'oiMbSpCy', 'oypbCiSM', 'pCMyiobS', 'yiCpoMbS', 'yoCMSibp', 'ypCSbMio'], ['FPcusOuzT', 'FPsOuzTcu', 'FczuTusPO', 'OuPucFszT', 'OuuczFTsP', 'PFOuzucsT', 'PuTFucOzs', 'cFOTPuzsu', 'cTuzuPOFs', 'csuuzTFPO', 'sFuPzuTOc', 'uPOFTczsu', 'uzuFOPcTs', 'zOcFsTuPu', 'zcsPuFOuT'], ['Mm', 'Mm', 'Mm', 'Mm', 'Mm', 'Mm', 'Mm', 'Mm', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM', 'mM']]