Most pictures I have seen around online of the 2015 Code 4 show the "CTS-XHP" marking on the base of the blade.
That would be with the writing going across it, like how Spyderco marks most of their knives. On the front side of the blade.
I have purchased four of the 2015 knives with Carpenter CTS-XHP and CTS-BD1 so far.
Two of them are the Recon 1 4-inch, with Tanto- and Clip-Points, with Olive Drab G10 and DLC-coating. These have the blade steel marked on the back of the blade under the new 2015 Cold Steel logo.
The next one is a Hold Out II (4-inch) with Olive Drab G10 and DLC-coating. This one has the blade steel marked under the old Cold Steel logo. On the back of the blade at the base.
The last one is the Voyager 4-inch Clip-Point with the blade steel marked under the new logo, just like the Recon 1s are.
I would think that this is a rolling change between models. As long as they are marked, I would consider them legit.
I haven't seen any fakes of the Code 4s yet. But I haven't been actively looking for them either.
To be sure, you might want to take pictures of the markings in question and post them.