Does Bulk Conversion Tag to Filename rewrite unchanged Filenames?

A year ago I was so blown away by mp3Tag that I converted 3000 mp3 filenames using tag information.
During the intervening period I have cleaned up the tags on about 10% of these tracks. So I would now like to regenerate file names for these changed tracks. Do I have to do it for all 3000 tracks or will mp3Tag not attempt to change the filenames of the 90% unchanged files?
If it changes all then my mirroring backup software will go into overdrive!

You could filter for or sort by files that have been modified after a certain date.
In general: MP3tag does not compare the before and after.