IT'S ALIVE !! IT WORKED !!
I booted a RAM session, mounted both pupsave files (old and new), deleted the following 2 folders from the old (non working) install:
/etc/cups
/usr/lib/cups
and replaced them with the folders from the new pupsave, and now CUPS-PDF works normally.
Previously, I had installed my hardware printer and hplip package in the new puppy install. After this "folder swap", the hardware printer works fine in the old puppy install.
What I was doing wrong in other occasions, is to copy folders or files from the session in use, to another pupsave file. It seems doing that, I was messing with the read only files in use being copied to the 2nd pupsave sfs. Booting a fresh RAM session and copying from one pupsave.sfs to another pupsave.sfs worked fine.
I want to thank you all who offered ideas and solutions. Thanks again.