I am using XxHash in my app and was assuming that – for the very same exact input – the resulting value would always be the same.

I have spotted however some irregular behavior when running in multithreaded contexts.
I created the excerpt below that reproduces the problem:

void reproduce()
{
    var scrubber = new MyScrambler("initialSeed");
    var input = "MyString";
    var tasks = new List<Task>();
    var scrubbedValuesList = new ConcurrentBag<string>();
    for (var i = 0; i < 100; i++)
    {
        tasks.Add(Task.Run(() =>
        {
            var scrubbedValue = scrubber.Scramble(input);
            scrubbedValuesList.Add(scrubbedValue);
        }));
    }

    Task.WaitAll(tasks.ToArray());
    Console.WriteLine($"distinct hashed values for input: [{input}]: nn ===> {string.Join("n ===> ", scrubbedValuesList.Distinct())}");
}

Running it often gives me multiple results, like

Seldom, I get a distinct result only.

Is this expected behavior ? What is it with the multithreaded context that makes it non deterministic ?