Currently, if two file names for export in the queue are identical (in the same directory), the second rendering round will overwrite the first. IMHO, there should be a warning either before adding the second identical file and directory name to the queue, or the automatic opening of a new dialog to save the second file under a new name (just like it currently works with already existent files in the output directory.
Use case: I recently cut only the actual music parts from a musical video (not knowing the titles of the songs yet), and inadvertently made a numbering error, so I had two files with something like “song_03” in my queue. Once I found the real titles, it caused a lot of confusion until I found that the first file was overwritten without a warning.