I think part of the confusion here is that “Approved” means “I agree with Akismet marking it as Spam.”
I logged into your forum and found the Akismet spam post. It looks like the staff member hit “Confirm Spam” so the akismet item was approved and in this case the post was deleted.
Regarding the double queuing, that is a separate issue. @Roman I don’t think Akismet should be triggered if a post was already approved by staff. Can you adjust the plugin so that doesn’t happen?