I'm following the discussion here and appreciate all the ideas offered so far.
Unfortunately I think I did all the things that have been suggested.
First, Dafydd Bevan, I saved the revised file via File Save As.
Second, I gave it a new name. It was "1992 cruise version2" The original was "1992 cruise"
Both the original and the revised files were save to the hard drive. The only thing they had in common was the folder they were located in.
Both files were visible as separate and properly named project files in that specified folder the next day.
Thank you gbainbridge for the archive link. I checked that, but the fellow there was using a archive disk of several project files and perhaps had version issues between what he had saved to a archive disk and what he retained on his HD. I think my problem in comparrison was more simple.
I haven't tried to repeat this process because I thought someone might have a solution other than it is a bug in PD9 that might be rare to encounter.
As always, warm thanks to all who have scratched your heads along with myself on this one and offered you ideas.
Mike