MVC - C# - How to remove duplicates from the array

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        int[] a = { 1, 2, 3, 2, 3, 1, 5, 5, 6 };
        int[] b = a.Distinct().ToArray();

or 

        int[] a = { 1, 2, 3, 2, 3, 1, 5, 5, 6 };
        a = a.Distinct().ToArray();