I think the RPT requirement for 2 ADFs isn't applicable to Twin LOC approaches.
Under Oz rules a private flight is allowed to do a Twin LOC approach. Also Aerial Work & Charter operations require two independent navaid systems. Two ADFs are not specified so a single ADF & a single VOR meet the navaid equipment requirement.
Good point about the difference between a LOC & an NDB. I was being a bit slack in my wording.