Yes, I figured out that once there is a ("true" not XMP hybrid) IPTC area created, for example by Nikon Transfer (or PM is setting are for such), then PM will continue to write a copy of the structured keywords into this area even if the preferences say not to write to IPTC. If there is no such IPTC field at all, then it will behave correctly and not write any IPTC info.
Responding to your reply, "Since you're no longer embedding IPTC data, ...."
Well, I would like to use the IPTC data field, however, with the way PM adds the second copy of the structured keywords WITH the extra spaces on each side of the divider, it makes IPTC impractical. My catalog software, IMatch, is very IPTC driven because the author is very comfortable re the stability of this area of the metadata to move info. in and out of, and LR, which I use occasionally, double books the structured keywords because it thinks the IPTC version is a different keyword with the spaces. I tested LR, by deleting the spaces in IPTC, (find and replace), and it worked great. But, I do not want to do find and replace step for each time I add a keyword.
IN summary, the program bugs in PM that affected me in this discussion are two:
1) For some reason PM Structured Keyword Panel, when it writes a copy of the structured keyword to IPTC, it adds spaces on each side of the word divider.
2) Even if you delete out all of the keywords from the IPTC field, and then turn off the option to write to IPTC, if there is any data in the IPTC field, the turn off option is then ignored and it will write to IPTC anyway.
Thanks for the great service and support,
Tom