I feel seperating them would probally be more useful for the new people. It usally dont take long to figgure out which "dulcimer" the question is about with a read asuming you know the difference to start with. Many dont.
It could be helpful for insterment speciffic things like double melody strings.. For things that are not insterment speciffic such what notes are in a given key It dosent really matter if the 2 are together as thes are more a music speciffic question that is the same on any insterment.
Dosent matter to me at all if theyre seperated or not.