The USAF B737 accident exposed an interesting example of Murphy's Law. If I recall correctly the USAF had a published general SOP which directed that once established on final instrument approach, you were not permitted to change a navaid frequency. When the B737 departed the first NDB (I understand that for some reason there was only one ADF on the aircraft - maybe a TACAN RMI was fitted) adherence to this SOP meant that the crew were not permitted to change frequency to the next NDB in the procedure. Obviously someone in USAF HQ figured that there was a risk of mis- selection, so they neatly removed that risk and caused a worse risk to surface.
The aircraft was never stabilised - it was high and fast from the beginning and the workload built up. That second beacon near the airport was vital as it defined the missed approach point as well as a tracking aid I think.
But the crew never selected it. They either forgot due to hurried unstable approach or they stuck to a dangerous SOP and did not select the next NDB.
On any normal twin locator approach (assuming two ADF in the aircraft), once the aircraft is comfortably tracking on final and having passed the first beacon, I prefer to now bring both ADF's up to the beacon ahead as a precaution against mis-selection and a general back up to what may be the missed approach point. Purely personal opinion though.