irnbru:
So is the site owner aware? A simple solution would be for the prev/next buttons not to contain the ?sid part.

irnbru:
For d4rkm4tter: it is not entirely fixed. Reproduction steps: Have a favorites collection where a problem somewhere in the middle is one of these duplicates. Now (while inside your favourites) go to the problem DIRECTLY BEFORE IT. Now click NEXT. It now takes you to completely the wrong place.

irnbru:
OK, I figured out what's causing the problem with Favorities, it's the ?sid=186 part which is interfering with it working.