How to avoid duplicate items on a listview

I have a string array of 3 elements and i have to display it on a listView having three columns,but,before each add have to avoid duplicate addition of elements to listview.

Following is the code where i add elements to the list.

            arr[0] = ip;
            arr[1] = hostname;
            arr[2] = macaddres;
            // Logic for Ping Reply Success
            ListViewItem item;
            if (this.InvokeRequired)
            {

                this.Invoke(new Action(() =>
                {

                    item = new ListViewItem(arr);

                    //**needed trick here to check for duplicate addition**
                        lstLocal.Items.Add(item);
                        int count = lstLocal.Items.Count;
                        toolStripStatusLabel4.Text = string.Format(count.ToString() + " Item(s)");
                    }
                }));
            }

The Containskey() and Contains()didn't work for me.