remove os elementos duplicatos de uma lista, mesmo que sejam dicionários

unique_dct_list.py

def unique_list(lst):
    backtrack = set()

    def hash_dicts(dct):
        if isinstance(dct, dict):
            return str(sorted((k, hash_dicts(v)) for k, v in dct.items()))
        return str(dct)

    def is_repeated(dct):
        hashable = hash_dicts(dct)
        if hashable in backtrack:
            return True
        backtrack.add(hashable)
        return False

    return [dct for dct in lst if not is_repeated(dct)]


print(unique_list(
    [
        {'action': 'allow', 'source': {}, 'destination': {}},
        {'action': 'allow', 'source': {}, 'destination': {}},
        {'action': 'allow', 'source': {}, 'destination': {}},
        {'action': 'allow', 'source': {'foo': 1, 'bar': 2}, 'destination': {}},
        {'action': 'allow', 'source': {'bar': 2, 'foo': 1}, 'destination': {}}
    ]
))