After getting a new MacBook Pro recently, I decided to reuse my old MacBook Pro as a home server. I reformatted the disk and reinstalled OS X, giving the computer a different hostname (let's call it NewHostname) in the process.
Now I want to back up the computer to the same Time Capsule I was using before. However, there is already an encrypted backup of the computer on that Time Capsule from when it was still called OldHostname. When I try to set up Time Machine, it returns an error message saying "The disk "DiskName" already contains an encrypted backup for this computer." This appears to be referring to the old sparsebundle image.
The only options Time Machine offers are to continue using the old sparsebundle or to erase it and start a new encrypted backup. Is there any way I could keep the old sparsebundle and start a new backup? And how does it even know that this encrypted file happens to correspond to this computer when the hostnames don't even match?
Note: I've already tried renaming the file in Finder from OldHostname.sparsebundle to OldHostname-old.sparsebundle, but that didn't work.