Did Time Machine put 274 GB of data in my Volumes directory?

Question

My first hint that something was wrong was that Carbon Copy Cloner complained that my 600GB encrypted disk image wasn't big enough to hold my backup.
I knew that couldn't be write. My data was roughly 300GB.
So I fired up the superb (free) OmniDiskSweeper and found there were 274GB of data in my /Volumes directory (hidden system folder, to visit it with Finder use "Go To Folder" and type Volumes.
That Folder normally holds Unix Aliases, not files.
It turned out to hold two copies of my hard drive, one fairly complete, the other a mere 40GB, both dated within one day of Jan 26, 2011. They were named after my Time Capsule hosted Time Machine image.
I'm pretty sure TIme Machine put them there during a Time Capsule backup. I've never seen reports of this, but I have seen reports of similar behaviors with disrupted Time Machine backups to a local firewire drive.
I deleted the 600,000+ files and OmniDiskSweeper reported Volumes now uses 12kb.
Has anyone else heard reports of this? I'd guess I'm not the only person who's experienced this, though some friends claim I'm cursed. I don't think it impacted my backups much, neither Time Machine nor SuperDuper nor CarbonCopyCloner actually copy the /Volumes folder, there's not supposed to be anything important there.

Answer 1

Maybe a good tip to prevent dopplegangers hidden in Bombich CCC website?
http://help.bombich.com/kb/dmg-and-remote/a-caveat-for-backing-up-to-a-remote-ma cintosh-that-has-no-user-logged-in
I am going to do this and see if it prevents this problem from happening
A copy of the link's text follows because he sometimes deprecates a real gem posted in his support site. 
A caveat for backing up to a remote Macintosh that has no user logged in
For "improved detachability", Mac OS X will unmount any non-internal volumes that are attached to the system when you log out. So, for example, if you log out of your computer while a USB or Firewire hard drive enclosure is attached, you can detach those hard drive enclosures from the system without having to manually unmount them first. This is a good thing — it would be annoying if you had to log back in to your system just to eject a drive. The downside of this, though, is that if you have a scheduled backup task that runs when no user is logged in, the destination volume may be unavailable. For a local backup, CCC will attempt to manually mount the destination volume. When the destination of your backup task is a remote Macintosh, though, CCC will not be able to mount that volume prior to backing up.
If you anticipate backing up to a remote Macintosh that may be sitting at the loginwindow, you can change the behavior of Mac OS X to not unmount detachable volumes. To change this behavior, run this command in the Terminal application on the remote machine:
sudo defaults write /Library/Preferences/SystemConfiguration/autodiskmount AutomountDisksWithoutUserLogin -bool YES
Note for Snow Leopard users: This workaround does not work on Snow Leopard 10.6.0 to 10.6.3. If you require this functionality, please apply the 10.6.4 update (or the latest available) for the best experience.