You can check,
inside pfd options you can see what nav source you can set to which Nav1/2 indicator, also primary nav source. Each source has different arrow type, if set adf no nav1 and vor2 freq to nav2 you then see one line blue arrow as ndb and double line vor2 direction, also in case of dme equiped source also distance. You can have at one time 3 different navigation sources what is very good.