Cloning a volume using Apple Software Restore (the asr command in Terminal) will clone any catalog damage too. If the reason you want to make the clone is to repair damage, that's not going to help.
SuperDuper will make a file-level copy, handling multi-linked files correctly, and will produce a copy without catalog damage even if the source has catalog damage. (But if the source catalog is damaged, the copy may not finish, and even if it finishes the new copy may have other non-catalog inconsistencies that make it unusable.)
As of Snow Leopard, a simple Finder drag-copy from one volume to another also correctly clones a Time Machine backup. (Same caveats as for SuperDuper. If the original has catalog damage, the copy my never finish, or may be unusable. But there will be no catalog damage in the copy even if the original had catalog damage.)
