EXIF and Continuous Shooting

I've just been sorting through my photos and there are many duplicates from past incorrect backups. I'm using Expression Media to sort via EXIF time date but this only goes down to the second - so it's not possible to easily determine if the shot is a duplicate or a sequence of frames within that second.

Any suggestion - I have Expression Media, Aperture and iPhoto at my disposal (and 105,000 photo's)