It could be a authorized copy--Saks bought the rights to copy it and had it manufactured in the US. Chanel would have provided a reference for purchasing the fabric, buttons, etc. like the orig.
What kind of buttonholes does it have? Is the lining sewn in by hand or machine at the armhole. Do the buttonholes on the sleeve work?
My book The Couture Cardigan Jacket to be published in the fall discusses these copies.