The antec one looks pretty similar to the filco "tsubasa" I think it was that was on ebay recently.
Maybe it's a rebranded filco?
EDIT:
Yeah, it's gotta be, take a look the layout on the antec:
And on the filco:
Other than the enter key of course, but that changes by area(filco looks like an eastern layout).
And the cutaway at the top for the f keys as well as the fact that they're both some form of white ALPS.