Bizarre: copy of stack is a prior version of the original

[depstein at att.net]

I have a stack that exhibits the following behavior, which I have never encountered before and do not understand.  

The currently saved version of this stack includes a number of obvious changes made since a previously saved version.  When I make a copy of this revised version, the COPY does not reflect those changes.  In other words, I choose "File/Duplicate" in the Mac OS9 finder, or I drag the file to another server, but instead of getting the copy I expect I get a copy of a prior version of my file.  The original remains the correct, "revised" version, but I can't make an accurate, up to date copy of it.

Has anyone experienced this, or does anyone understand what might be happening?

David Epstein