They are clearly the same slippers. When the photo is enlarged and closely examined, the white pattern on the top of the shoes is visible, confirming the match. Their positioning suggests they were taken off in a hurry—almost as if they were kicked off before going down the stairs. If there was a change in shoes as you suggested then you would expect the slippers to be placed together and most likely next to the seat so she could sit and change shoes. I don’t Fgm would be bending down to put shoes on when there were seats right there. In the same photo, you can also see L’s stroller, the Spider-Man toy, the newspaper FGM had been reading on the seat where she was sitting, and William’s drawing still on the floor. The photo appears to have been taken not long after William disappeared, possibly shortly after police arrived, as everything on the patio remains exactly as it was beforehand.