I'm not sure what you mean by "import it". The bug report included the two RSS items with the same date, but not the full feed, so you couldn't just paste the items into a file and feed it to Liferea.
I've created an RSS file out of the feed items you posted. (attached) and added it to liferea as a subscription from a local file.
When I add it, it has 2 unread items. Then I click on one and then update again it says it has 1 unread.Then click on the other and it says it has no unread, even after I update it.
So it seems to be working ok here.Let me know if it's still a problem for you or if you know of a better way to reproduce the problem.
Tested with liferea 1.8.6-1.1 in Debian Wheezy. Thanks for your time. -David Smith
test.rss
Description: application/rss