It's not so rare that different release dates for a Japanese game are given by the Japanese and English wikipedia articles (and it's just one day, thus I assume it's due to the time-zone difference). For this particular game, however, every release info on them is considerably different.
http://ja.wikipedia.org/
2005-06-16
Choushittou Caduceus
2005-10-11
Trauma Center: Under the Knife
2006-03-31
Trauma Center: Under the Knife
http://en.wikipedia.org
2005-06-30
Choushittou Caduceus
2005-10-04
Trauma Center: Under the Knife
2006-04-28
Trauma Center: Under the Knife
I generally rely on the Japanese Wikipedia for Eastern release dates but at the same time, I also trust the English Wikipedia at least for Western release dates. Really don't know which is right in this case, and maybe I should gather info for each release...