Did they edit their question at some point because I see this.
d:\myfolder\archive\nina\documents\exist.txt
d:\myfolder\archive\nina\documents\today\not_copied.txt
That was not edited; that is not the problem. The requirement appears to be this:
d:\myfolder\archive\nina\documents\exist.txt
d:\myfolder\archive\nina\documents\today\not_copied.txt
rename to
d:\myfolder\archive\nina\documents\today\copied.txt
See? Same folder for copied.txt (the desired end result) I guess this could be an error.
That is
Look in folder $NAME\documents for a file called exists.txt
If it is found:
Look in folder $NAME\documents\today for a file called not_copied.txt
If that is found:
Rename it to copied_txt
I appear to have set the cat among the pigeons by asking innocently "What happens if copied.txt already exists?".
Looking behind the code for a moment, I am wondering if the desired end result is to copy or move not_copied.txt
to another folder as copied.txt. That is, conceptually, the names copied and not_copied clash with the idea of 'rename'. Copy duplicates a file; rename leaves it in place. The question of what to do if the desired destination file place/name already exists still remains, though.