bfa_thumb() ignores existing thumbnail

I have an irritating problem, not a bug. I am trying out Montezuma, which by the way seems even more awesome than Atahualpa, and call bfa_thumb() from the loop with

When I upload a media file named "ralph.jpg", I see that a thumbnail has been been created in the media library directory called "ralph-620x180.jpg" because I've added support for that thumbnail size into the theme.

So, I expect that thumbnail will be used by the theme because the overview of bfa_thumb says:

However, when I choose "ralph.jpg" as a featured image on a post and view the post on the front page, the theme has created "ralph-620x180-1.jpg". Note the suffix which has been postpended to the name. It appears that bfa_thumb() always creates a new thumbnail even when one pre-exists.

The irritating part of this has to do with the steps necessary to fix a bady cropped thumbnail. I am training my client to use Post Thumbnail Editor which creates a new thumbnail without the suffix. Then my client must visit the server and rename files. (Yuck. If you knew this client, you'd be worrying too.)

I'll try to dive into your code to force bfa_thumb() to alway overwrite the thumbnail without postpending "-1" but best if you could correct me or correct the code.

The theme is live on a server but not active yet, Try http://artsmeme.com/?theme=artsmemeV2 to see the site. (Note I am replacing an Atahualpa child with a Montezuma child!)