> When I first started applying keywords to my photos, I labeled people in the "best practices" way you identify people in one field -- using "last, first". This worked fine.
You mean Last Name, First Name? You might have been better off using underscores, e.g. Doe_John.
> At some point, Thumbs Plus started getting confused about those existing keywords in image files when I re-scanned them, and treated them as two separate keywords.
Sounds like something that could have happened if you've imported data from an exported-to-txt database, or, more likely, when you have set TP to generate database keywords from IPTC keywords.
> Any ideas on how I can possibly recover from this disaster?
Assuming that you'll want to synchronize your database and IPTC keywords for each file.. I can only think of a long and tedious task, along these lines:
1) Export database to text and use a capable text editor to make a file listing looking somewhat like this, which contains all your database keywords:
"d:\photos\2012\pic001.jpg" "Doe John"
"d:\photos\2013\pic009.jpg" "Smith Lucie"
"d:\photos\2013\pic010.jpg" "Doe Hank"
2) Use EXIFTOOL to extract IPTC keywords from your files, and produce a similar file listing from those.
3) Now you have a list for both types of keywords. Find some way to combine them and remove duplicates.
4) Use EXIFTOOL in a looong batchfile to assign the cleaned-up keywords to the image files.
5) Thumbnail the files in TP9, with TP auto-generating database keywords from IPTC keywords.
6) Now your IPTC and database keywords are in sync. In the future, add IPTC keywords to new images first, then thumbnail them in TP..
