"Where ALL Roman gods simply copies of greek ones?"
No, and while many of them came from a common cultural substratum - probably the Indo-European one - which made easier to map them (as you can even map gods from other cultures as well) , there were some more specific ones.
Janus is a good example of a god which had no Greek counterpart.
Julius believed there were so many gods you could even add a new one - himself...
Biting the hand that feeds IT
