rear hub seal or stub axle seal?

whilst replacing the shoes on my 90 i noticed that oil was finding it's way onto the inside of the brake backplate it seems to be coming from where the hub meets the backplate, i have checked the old haynes and cannot work out if it is the rear hub seal or the stub axle seal that needs sorting, any ideas?

Change both to be on the safe side. Not expensive to buy, just costs time...