C#

public partial class UserControl1 : UserControl
{
    public event EventHandler Button1Click;

    public UserControl1()
    {
        InitializeComponent();
        button1.Click += new EventHandler(button1_Click);
    }

    void button1_Click(object sender, EventArgs e)
    {
        OnButton1Click(e);
    }

    protected virtual void OnButton1Click(EventArgs e)
    {
        EventHandler eh = Button1Click;
        if (eh != null)
            eh(this, e);
    }
}

public class MyListOfObjects : List<MyObject>{}

public void AddUnique(MyObject obj)

int idx = oldList.BinarySearch(currentObject);
if(idx<0)//does not contain your code here ...

for(int i = GetLengthOfLongestList(); i>0; i--)
{
try
{
var currentNewObject=newList[i];
}
catch
{
//do some stuff here to avoid use later
}
and a 
try
{
var currentOldObject=oldList[i];
}
catch
{
//do some stuff here to avoid use later
}
/after checks
oldList.removeAt(i);
//or
oldList.add(currentNewObject);
}
}