If this was developed in a SP 445, could it be that the film was loaded emulsion-side facing the holder, rather than outward?

(It looks like the short black lines on the left might respond with the small lamella at the bottom of the holder, and the horizontal light line is roughly where the centre stiffener would run - assuming that your image shows one of the short sides of the film.)

If so, that might then be quite easy to replicate, at least roughly...