My apologies for resurrecting an older thread, but I'm not seeing this behaviour of Time Machine "Catching up" so I'm not sure if there's something I'm missing or there's a bug somewhere.
I was having the typical problems with fragmentation in putting a Boot Camp partition back on my system, and a Super Duper restore has always been a far faster way to "defrag" my internal drive than bothering with an actual defragmentation tool
Unfortunately, after a restore, Time Machine wants to re-backup 64GB of data, which is approximately my entire internal drive less any specifically excluded files (like my Aperture library). To add insult to injury, it takes a ridiculously long time to do this -- longer than it would to wipe out the Time Machine backup and start over from scratch.
This may not be a Super Duper specific problem, mind you... My wife's MacBook had a failure without a Super Duper backup, so we restored her unit from Time Machine itself, and even then it wanted to back up the entire thing
again.
Any ideas or suggestions would be greatly appreciated, however -- even if its just something I can tweak to avoid this problem next time around. Not only is the time it takes to do another full TM backup quite irritating, but the fact is that I'll end up stuck with 60+ GB of redundant data in my TM backup.