I think I read somewhere that you have both parts of a double weapon have to be enchanted separately but I can´t find the passage. Can someone point it out where I can find it or is it FAQ, Sage Advice or House Rule?
In 3.0 it was mentioned in several places, e.g. in the Equipment section about shields and weapons (e.g. it said for shields & spikes that you have to enchant it separately for attack or protection purposes).