object getting modifed

Hi,

I am writing Under Test Code for testing the below method of my code

public int[] getsomething(string num)
{
 int[] numlist;
  numlist =getnumlist("",num);
  if (reversenumlist == true)
  {
    Array.Reverse(numlist);
  }
return (numlist);
}

My Unit Testing is like this

[TestMethod]
        public void getsomething_test()
        {

            int[] expected = { 1, 2, 3 };
            int[] actual;

            TOEVelocityColumn toeVelColFake = Isolate.Fake.Instance<TOEVelocityColumn>();
            Isolate.WhenCalled(() => toeVelColFake.getnumlist("", "1")).WillReturn(expected);
            Isolate.WhenCalled(() => toeVelColFake.getsomething("1")).CallOriginal();
            Isolate.WhenCalled(() => toeVelColFake.ReverseNozzleDirection).WillReturn(true);
          
            actual = toeVelColFake.getsomething("1");
            
            Assert.AreNotEqual(expected, actual);
     }

As you see, in the UTC, I am returning the expected variable on a method call.
In Act region, when I call the actual method, I am getting the reverse list but the expected variable also is getting reverse as a result the assert is failing because both expected and actual are getting reversed.
Can you please let me know how can I make sure that the expected variable will not get reverse?

James