From the 2.3 release notes page:
1.- "You can now drag and drop files directly from your desktop straight into file areas! "
2.- "Files can be created as "aliases/shortcuts" of other files. This allows you to, for example, use a single file in your private files area multiple times in all your courses. If you update the original file then all the aliases will automatically update!"
Unfortunately, features 1 and 2 are not compatible. Let me explain.
There are 2 ways to upload a file and we would think that those two ways also apply to the "update" of an original file in e.g. the "My private files" repository.
a) using the file picker: Files / Add / Upload a file and upload the new version of your original file. Then you are warned that "File exists" "A file with that name has already been attached" and prompted to either Overwrite or Rename the original file (or Cancel). Of course, for updating the original file you have to Overwrite it. This works as expected.
b) using the drag & drop new feature : if you try to drag and drop the new version of an already uploaded file, you are not warned that "File exists" and the new version of our original file is automatically renamed (e.g. catimage.jpg is renamed to catimage_2.jpg).
If people agree that this not an "intended feature" but a bug I will post a bug report.