Best Duet of All time?

I was at a friend's house, and he and his wife were watching a show that had the 100 best duets of all time. I got sucked into watching, and it said that the #1 duet of all time was Kenny Rogers and Dolly Parton's "Islands In The Sea." Surely this has to be incorrect. Does anyone else agree? What you are your suggetions for the #1 duet of all time?