New (correct?) romanizations come from TYPE-MOON Ace 11 where all the servants were also written in English.
The old name (which AFAIK was the only official one) came from an in-game item, but I guess they decided to change it. At least it looks like they're sticking with it officially:
http://www.aniplex.co.jp/fate-gp/#goods
They're also using Altria instead of Artoria now ... yay consistency!