Arthur's Knights: Tales of Chivalry and Arthur's Knights: Origins of Excalibur do appear to be the same game. Tales was published by DreamCatcher in the US while Origins was published by Cryo in EU.
From GameFaqs about Arthur's Knights:Tales of Chivalry (US):
Also Known As: Arthur's Knights: Origins of Excalibur (EU)
Release Dates of Both Games PS: The sequel, Arthur's Knights II (2) or Chapter II is called The Secret of Merlin.