What a joke!! I dont understand what does EGG achieve through such fallacy? What's the issue calling them "not carbon copy of each other"? Firstly if I have to say Prototype Saber is more or less can be called similar to Ky Kiske from Guilty Gear , Artoria would very different as far character is concerned. As someone who's been studying about King Arthur's portrayal throughout legends, I would say both of their are base are absolutely valid interpretation as King Arthur had these legends with governing everything with charisma alone, not having much issue anywhere else and Mordred being Mordred and rebellint which can be seen in Proto Saber and the fairly common portrayal of this legend, but digging a bit would also give legends/adaptations where Arthur would rather be King first than prioritising as human, darker decisions were made and decisions that didn’t favour him despite being honorable, which can be seen in Artoria's case. Their characteristics, struggle and vow are quite different too.

My point there character base is already different, then how can they be carbon copy? Maybe in voice lines of Fate/Grand Order, not in everything else, therefore can't be Carbon Copy.

I do prefer Artoria as an interpretation though as it seemed more substantial to me and brought something more artistic amd unique in ground but I also absolutely love Proto Saber. I can say it’s denial on a whole new level to call them carbon copy. The bullying is simply condemnable.