Anne Ross makes the point (with regards to one stone) "we must bear in mind that the choice of horns is likely to have been dictated by the space available for the addition of this feature, and those of a goat may only have been selected because they fitted easily into the overall design".

I am pretty certain that there were a number of seperate gods in those days. Some of these gods were related, some forming triads of particular power, others seen as different aspects of the same god.

But I find it highly doubtful that one god known for goat horns would have been portrayed as having rams horns.

This is the times of the pre-literate - visual communication was therefore of increased importance - images had to convey an obvious message - one re-inforced by the bards. This was also a time of strict adherance to the bards message - the bard being the bringer of truth - written words could lie but a bard could not. I think everyone knew that such and such a god had X horns, and they all know why he/she had them - they would have been part and parcel of the god myth.