I think it's ok with this. Update the tests, then close the issue and republish after that.

    @test.it('Random tests')
    def _():
        THRESHOLD = 99 ** 9999
        for _ in range(200):
            if randint(0,1):
                rand_number = randint(0, THRESHOLD)
            else:
                rand_number = ... # some other way to compute the number, to be SURE it will lead to something else than `nope`
            exp = solution(rand_number)
            test.assert_equals(is_atone(rand_number), exp)

You need to select python version 3.8, and then there will be no error.

Yes, there's clearly a contradiction between the instructions and the test.

Can you help them to remove numbers such that their list contains each number only up to N times, without changing the order?

Keeping the order is part of the task. So, if you don't keep it, the goal wasn't achieved.