for some reason publisher change the cover title to Soulcalibur II, but main menu title is still Soul Calibur II. so, I think we must name it exact as (U) version.
There have been some discussions about this before.. the official title is Soulcalibur not Soul Calibur: http://en.wikipedia.org/wiki/Soulcalibur , http://www.soulcalibur.com/ etc