I download ical events from a website regularly. I get emails for different events as they are announced and I click the link to add to my calendar. The problem is that when I download a new event, iCal deletes the previous event even though the events have different, titles, times, URLs, etc. I'd like to keep previous evens as a historical record. Worst of all, events are being deleted before they even occur when I have multiple events scheduled closly. What am I doing wrong?