[Ermite]

Ещё как вариант

<script>
  var list = [
    { 
      Id: 1,
      Name: "name1",
      ShortName: "shortname1",
      ParentID: 11,
      Login: "login1"
    },
    {
      Id: 2,
      Name: "name2",
      ShortName: "shortname2",
      ParentID: 22,
      Login: "login2"
    }
  ];
  var kusts = [];
  for (let i = 0; i < list.length; i++) {
	kusts[i] = Object.assign({}, list[i]);
  }
  kusts[0].Id = 3;
  alert(`${kusts[0].Id}, ${list[0].Id}`);
</script>