@kovid and @BR:
Kovid explained that the target dir never shows any files present there, so that's a fact and I can live with that. Besides I can and do normally use Windows Explorer to keep an eye on those existing files, if any, in the target dir.
But sometimes a previous stored file still lingers there because I'm lazy and do not check whether a same file already is available in that target dir. And so when I save the (altered) file again into that target dir, I encounter the *real* problem:
Calibre tells me the file is saved, issues no warning that a file with the same name is already there (which one would expect), and when I use the Windows Explorer (fresh invocation) I see that the date/time of the file is still reflecting the old date/time (say from the day before) of the previous save.
In the past I also did check whether the latest updates where present in that stored file and they were not. I confess I did not checked that last fact recently, but was triggered again by the unaltered date/time.
And as I have seen this behavior a long time (at least several years and versions back) I decided that it was now time to mention it in order to initiate perhaps a solution.
But as Kovid does not seem to to be able to reproduce this behavior it might well be some local personal PC quirk (ok, my trusty PC is old
).