Rear disc problems still

[hb69]

So following on from my last post about not being able to get the rear discs off my ph1 i used the biggest hammer i had but they still wouldnt come off. So i unbolted the hub and disc etc from the rear beam. Now im confused by what ive got. Ive removed the camber shim that was on there and took a pic of whats there

The square bit of metal thats part of the hub on the right is not moving, the one in the middle is free.

The hub nut is off, is there anything i could be missing?

Any help is appreciated