Bug: Duplicate posts at every processing of the feed

Seems there is a big bug in the plugin: It generates posts every time the feed get´s processed and doesn´t care about duplicates. I tried every setting and spent hours of work on this issue - think it should not be so complicated to setup autobloging.

The feed I used is

The duplicates even get the same permalink when the posts are not automatically published. I would prefer publishing the posts automatically, but this is useless because you get a lot of duplicated content - sometimes the same article is posted more than 40 times! Because of this the autoblogging doesn´t make any sense - it´s more work finding all the duplicates and deleting them, than writing articles by hand.

I saw other users have the same issues and don´t understand why this bug is not solved. This error unfortunately makes the whole plugin superfluous. Hope you have a money back guarantee.

I´m using WordPress version 3.8.1 and version of the plugin.