Your suggestion has been noted, no doubt. But so has the linked one with almost the same title and description of the function.
There have also been numerous discussions about the treatment of alleged duplicates, see e.g. here (seriously)
In general: AFAI get the summary, the same data in the tag fields does not qualify to identify a real duplicate.
So for serious collectors it would be mandatory to investigate for each file if it is a real duplicate or just the tag data is insufficient.
As you see that the feature has been asked some time ago (and there are other threads that suggest other functions to work around the problem of duplicate file names) I suggest for the meantime the following:
Rename all new files with Convert>Tag-Filename
Format string: %artist% - %title% (%_counter%)
Then move them to the new location with the method that you have used before and now all files that cannot be renamed stay with a number in parenthesis.
You can now filter for these files with
%_filename% MATCHES "\(\d+\)"
and check if they are real duplicates.