Normally the DH is 200 ft for a Cat1 approach. The minimum on DUS 23R is higher and thus "non-standard".
Our company minimums state: DH 220 ft (DA 350) for the "normal Cat1" (normally it would be 200 ft)
Then the other minimum states: DH 230 ft (DA 360). Here it is a question of the A/C's wingspan (being between 60-65m) or the vertical flight path of the wheels and the glide path antenna of 6-7.3 metres.
Thus the reason is a "non-standard" minimum.
There is a 1° difference between the ILS course and RWY course (ILS 234° vs. RWY 233°).
The GP is 3°.
Fly according to what the chart says (provided it is up-dated).
Safe flying
