As others have mentioned, the existence of the two forms oriented and orientated is one of the many differences that American English has from British English.
I have noticed this in American television programmes where American people have used the alternatives orient and oriented. This has always stood out as different and odd to me. Not only to me. It has been noticed by relatives when I watch television with them. They have commented on how different and odd this sounds to them as British people. They, like me, had not heard it until quite recently, in American television programmes.
It's different and odd because this is not normal in the UK. In all my life, I have only heard fellow British people use the words orientate and orientated. This is what I learnt, as a child.
My personal experiences are confirmed by the following dictionary entry for orientate, which mentions “(US orient)”: http://dictionary.cambridge.org/dictionary/british/orientate_1?q=orientate