How can I easily delete duplicate files in old Time Machine archives?

Question

I have multiple older Time Machine archives from different Macs that I have been going through manually and picking files out and copying them to another drive file by file. I'm running into massive quantities of duplicate files and the biggest problem is muliple iphoto pictures including the same picture in different sizes.
I wanted to give up and just throw the whole Time Machine archive onto another disk so I could format the one it was on and use it for something else. But I got a message reading, "The backup can’t be copied because the backup volume doesn’t have ownership enabled." So I went to manually copy each "Macintosh HD" folder for each date into it's their own respective folders. It worked but required my password for each folder and each of the 19 folders were all ~75GB. Which is impossible because all of that data was on a 500GB drive.
What should I do? This has become a two month long nightmare.

Answer 1

I really don't know exactly, but since no one else has a answer I'll give it a shot.
I don't know much about TimeMachine at all, however I did assist someone that their TM was corrupted and they needed to salvage what they could off the drive, so I'll start with that.
There is software called Data Rescue and it's designed to read the 1's and 0's of any data on the drive, deleted or not, regardless of the file structure, and output the results to another drive.
TimeMachine tries to save space, so it uses what appears to be duplicate files, but contain no data as they are placemarks for files in later states that went unchanged from the previous states.
If Data Rescue has the option of recovering files independently of the file/folder structure this would result in all your files from the recoved TM drive being on all one level on the second drive.
From that second drive one could run software called DeCloner, which would flag the actual duplicate files of content, not just by name.
The next stage perhaps would be to eliminate files with no data, the placeholders, using the Finder "size" as a sorting option.
Saving all this remaining content to another drive to work on further, perhaps all the remaining image files can be seperated, sorted according to largest size, the largest ones (usually the ones you want to keep as they contain more quality)  and opened into iPhoto or Aperture for further refinement as you add a small batches of smaller image sizes in to compare with the larger versions for duplicates/unwanted sizes.