In the days of the Roman empire, the dieties of the Greeks and Romans were identified with each other, but had different names such as (Zeus,Jupiter), (HeraJuno),etc. However for some reason Apollo was the name used by both. Why?
From what I understand it is because there was no obvious Roman god that matched Apollo's place in the pantheon. So it was a far more direct borrow from the Greeks. There had been cults worshipping Apollo in the early part of the Roman Empire, which isn't all that surprising given the spread of Greek influence at the time, and with no obvious counterpart the name simply stuck. That's my take on it, anyway.
