I heard that there's this thing called "Google". If you aren't familiar with it, after you click the link below, you will be taken to a page with a bunch of links and short descriptions of the sites. Beware that some of the listings near the top and right column are advertisements. It's a pretty neat service. They claim there were over 2 million replies to my query, and that it only took an amazing .51 seconds to accumulate the date. Give it a try:
remove duplicate excel - Google Search
Seriously, though.... I was actually just playing around with the exact same issue today. Problem is, I suck so bad with excel that I couldn't even get it to work after following the tutorials.....