I understand what's going on now. I have made a setting change to have the newest post listed at the top of the thread.
I thought this setting would have changed the front page of the website to display the newest posts in chronological order. It doesn't do this and simply reverses the post order, thereby making me think that the photos were posted twice; once at the top of the thread page and then at the bottom of the thread page.
Anyway, i've worked it out.
Is there a setting somewhere to have all the new posts for the day listed on a separate page, so you don't have to got to every post to check out if someone has posted a comment?
Fabian