Hi is there an option I can make mp3tag to auto append (2) to file name that already existed in the same location? instead having to manually rename it and add 2 end of the file name
No, no such option.
A duplicate filename should be the indication that something is not quite up to the mark and needs investication.
If you are not sure that renaming will be successful then you could add a suffix yourself in one go and then filter for the files that have this suffix and remove it in a second run.
You will then be left with the ones that cannot be renamed as they still have the suffix.
Okay thanks for the quick reply! I shall do that