I've found something. I'm not sure if it is interesting, let me know and see below.
In the first screenshot if I right-click on the small blue icon - instead of the topic title - a new tab is opened and the clicked topic is displayed correctly. The original page stays there (no double openeing). I've put a red circle around the small icon.
Now, looking at the destination in the Safari status bar show the following for the normal "Topic Title" click.
Clicking on the small blue icon shows:
You can see the difference on the act=