Can I move a Time Machine backup to a different partition on the same external drive?

It's even more complicated than that. I'd like to move the TM backup for machine 'Mac1' from the first partition on a drive to a second partition on the same external USB drive that already contains a TM backup for machine 'Mac2'. (The TM backup for 'Mac1' has run out of space and is beginning to delete older file versions to make room for new ones)

I remember reading that TM can backup different computers to the same external drive, and the explanation was that each computer's backup is kept in a different subfolder of the backups.backupdb drive. So In theory, it seems like I can just copy the sub folder backups.backupdb/mac1 in partition 1 to the folder backups.backupdb on partition 2. So I tried it, but even though I engaged my admin credentials on request, the operating system wouldn't let me do it. It said I didn't have the proper permissions.

Two facts that may be pertinent.

1. When I 'get info' for the volume containing the 'mac2' backup (target volume) and unlock the lock, there is no 'ignore ownership' option given. However, by using Disk Utility I am able to see that the target volume value for 'Owners Enabled' is No.
2. I'm thinking just dragging a TM backup (sub) folder from one Backups.backupdb folder to another doesn't modify possibly hidden data stored in the target Backups.backupdb folder that helps it manage TM backups for more than one machine.

So - the question (which is the subject of this post) remains. And if the answer is yes, how do I do it considering the two facts I mentioned above.