the Deppelink functionality seems to have a bug. Once the link to the same post has been selected once, whether or not the setting are changed again, the posts will continue to be linked.
The functionality is great, but it should be expanded a lot. Have a look at seo smarty links.
It allows to select for example if links can or cannot be included into the headings, or if auto link should appear in post, pages or both.
These two are very fundamental part of an auto link plugin.