A great new feature in Apple's Garageband is the multi take feature.
When you record a track, and the song is set to repeat after so many
measures, garageband will record multiple takes as you play. What I
like to do is duplicate the track, copy the file to the new track,
and then I can listen to take 1 in track 1 and listen to take two in
the copied track. Give it a try! Svend - www.svend007.com