I don't think there's any easy way for argparse to automatically do what you want. However, there's a simple workaround - just use the dest= argument and specify two different destinations:

>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('--verbose', action='store_true', dest='verbose_main')
>>> subparsers = parser.add_subparsers(help='command', dest='command')
>>> cmd1_parser = subparsers.add_parser('command')
>>> cmd1_parser.add_argument('--verbose', action='store_true', dest='verbose_sub')
>>> parser.parse_args(['command', '--verbose'])
Namespace(command='command', verbose_main=False, verbose_sub=True)
>>> parser.parse_args(['--verbose', 'command'])
Namespace(command='command', verbose_main=True, verbose_sub=False)

Closing as a wontfix, but feel free to reopen if you want to provide a patch for something.