The front set of 'hooks' held the rear of the tank, and the rear set were the deflectors. When the tank was jettisoned, the airflow, at the front of the tank, caused it to fall away 'nose down', so the rear 'hooks / deflectors' then 'caught' the rear of the tank, allowing it to clear the underside of the aircraft sufficiently to be able to tumble away without fouling the rear fuselage, or, more importantly, the tail planes / elevators.
Those model kits that include the hooks / deflectors, normally only have the rear, wider spaced set, assuming that the modeller will fit the tank, when the locating hooks would be covered by the rear of the tank, and not be visible .
Before proceeding with any sanding on the cannon mounts, note that the early cannon installation (i.e MkIIb and MkVb), in what was basically the 'A' wing, had a reinforcing plate on the leading edge. When the later 'C' and 'E'' wing were introduced, on the late MkV's, and the Mk.IX onwards, the later version of the cannon, and, of course, the wing design / construction, did not need this.
Again, using the Duxford based MkVb, the reinforcing 'plate' can be clearly seen in the pic below.