Super Duper and Apple Software Restore run in Terminal can clone a Time Machine volume.
Here is some recycled text from the old MacFixIt forums. I have not tried ASR since:
Syntax:
sudo asr restore --source /Volumes/Old\ Disk --target /Volumes/New\ Disk -erase
To make a clone of a Time Machine volume using Apple Software Restore (asr) in Terminal:
First, turn Time Machine off using the Time Machine pane of System Preferences.
Type (or better yet, copy and paste into the Terminal window) the next line:
sudo asr restore --source
Note the space character after the second “e†character in the word “restoreâ€.
Leave a space after the “e†character in the word “sourceâ€.
Drag the icon of the original Time Machine volume to the Terminal window. The pathname is pasted in for you, followed by a space character.
Type:
--target
Leave a space after the final “t†character in the word “targetâ€.
Drag the icon of the volume you intend to use as the new Time Machine volume to the Terminal window. THIS VOLUME WILL BE ERASED.
The pathname is pasted in for you, followed by a space character.
Type:
-erase
Press the Return key, and enter your administrative password at the prompt.
The result should be two volumes with identical names but different UUID numbers
sudo asr restore --source /Volumes/G-MINI --target /Volumes/G-Drive_Q_232 -erase
MMT3sMBPC2D:~ MMT3$ sudo asr restore --source /Volumes/G-MINI --target /Volumes/G-Drive_Q_232 -erase
Validating target...done
Validating source...done
Erase contents of /dev/disk2s2 (/Volumes/G-Drive_Q_232)? [ny]: y
Erasing target device /dev/disk2s2...done
Validating sizes...
Not enough space on /dev/disk2s2 to restore
MMT3sMBPC2D:~ MMT3$
New attempt, using the 100 GB G-Drive_Q_100 with a new, much smaller Time Machine having only 4 backups. ( I will explain why I had to make a new Time Machine later, but I urge you NOT to try to make the amount of data you need to clone smaller by deleting any Time Machine backups, either using the Finder (always an error) or the Time Machine interface. I attempted to remove one old backup from my Time Machine last night, intending to remove several more so that the entire volume would fit on G-Drive_Q_232. After a few hours, the selected backup was still there and still able to be selected, so I started the removal process again. This morning, I found that my Time Machine had folders for all of the backups. Instead of deleting the one backup, almost everything from every backup was gone. The total number of files was 70. I noticed that something was wrong when Disk Utility took about six seconds to verify the volume, and did not mention checking multi-linked files. That is because there were no links. TechTool Pro found the same result.
MMT3sMBPC2D:~ MMT3$ sudo asr restore --source /Volumes/G-MINI --target /Volumes/G-Drive_Q_100 -erase
Password:
Validating target...done
Validating source...done
Erase contents of /dev/disk2s2 (/Volumes/G-Drive_Q_100)? [ny]: y
Erasing target device /dev/disk2s2...done
Validating sizes...done
Restoring ....10....20....30....40....50....60....70....80....90....100
Verifying ....10....20....30....40....50....60....70....80....90....100
Remounting target volume...done
Copying the Time Machine volume began at 12:53 EDT and was finished at 1:57 P.M. EDT. Verification began at 1:57 EDT and was completed at 2:33 EDT. So in my example, verification took a bit more than half as long as copying.
Verifying the new volume with Disk Utility:
Verifying volume “G-MINIâ€
Checking Journaled HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Checking multi-linked files.
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking multi-linked directories.
Checking volume bitmap.
Checking volume information.
The volume G-MINI appears to be OK.
