Use multiple AdRotator controls on one page - no duplicates

Is there a way to use two adrotators controls on one page and stop the same advert appearing at the same time in both controls?


I have the following but it doesn't work:
protected void AdRotator1_DataBound(object sender, EventArgs e)
    {
        if (AdRotator1 == AdRotator)
            AdRotator1.DataBind();
    }


thanks

...