ILS Problem - Cannot add to flight plan

[Roger Jay]

Using PlanGv3 (v3.2.2.167) in FSX.

I can see the ILS feathers & the information panel gives the details but when I right click on a feather the pop-up shows the frequency line as greyed out & I can't add it to the plan.
Looking in Plan-G_Log.txt I see many thousands of pairs of lines like this -

21:00:42.9 Add Sorted Waypoint error: An entry with the same key already exists.
21:00:42.9  41.874519 -071.554736 ZORNN

Help would be greatly appreciated!