Just for closure for all of you that have tried to help me with this issue, this is what I've done to get it working as best I can:
- Put a copy of both libraries in a new place on both computers (PC1 and PC2)
- Uninstalled Calibre and removed all settings (running the startup wizard wasn't working for me so I went to the extreme)
- Reinstalled Calibre on both computers and pointed each installation to the new folder on its own computer.
- Shut down Calibre on both computers
- Moved the library folder on PC1 to the synchronization folder
- Started Calibre on PC1
- Calibre couldn't find the library where it should be so it prompted me asking where it was
- I pointed it to the new location (in my synchronization folder) and told it it had moved and Calibre was happy with that on PC1
- Sync'd that folder to PC2
- Removed the library folders on PC2
- Started Calibre on PC2
- Calibre couldn't find the library where it should be so it prompted me asking where it was
- I pointed it to the new location on PC2 (in the synchronization folder) and told it it had moved and Calibre was happy with that on PC2
So now it works. There is one thing wrong where it keeps changing the names of the libraries on PC2 and showing "sync conflict" errors in the folders with the metadata.db files. Hopefully this won't cause too much trouble but I'm going to keep good backups in case something goes wrong. As I said in a previous post, the help files warn me against trying to do what I'm doing so I understand I'm do so at my own risk.
I don't know why this was so very difficult this time when I've done this before and it was much easier!
Thanks to everyone who offered suggestions and help!