Hi,
I have an issue with identical file names (but not duplicate files). In the Mac Finder, if a file with the same filename is placed/ copied in the same folder, it automatically adds an “index”:
Filename.pdf
Filename - Copy.pdf
Filename - Copy 2.pdf
In DT, these Filenames just remain identical. Is there a way to add an automatic index: e.g.
Filename.pdf
Filename-1.pdf
Filename-2.pdf
I appreicate any help. It is an issue I have never encountered in any OS so far 
This default batch processing configuration might be useful:
But duplicating files in DEVONthink adds an index too. Maybe these PDF documents have a title, see Info > Properties inspector, and then this title would be used in case of files duplicated in the Finder?
But it does not do this automatically, correct? I need to start this manually.
Yes. AFAICT, DT does rename the files, i.e. their names on disk change. But the displayed name does not, since in DT these two things are separate (like in Finder, which uses localized names for many objects and not the real object names, which are always English).
