Prevent duplicates?

[chrisspen]

This may be more of a feature request, but is there any way to prevent duplicates?

Each time I run the script with the default settings, it re-posts the same content, even if it's already been mirrored, leading to a lot of duplicate postings.

The default sort is "new", but this doesn't seem to imply things that are new but not already mirrored. Is there someway to exclude posts that have already been mirrored so the destination sub isn't flooded with duplicate posts?