You're doubting the possibility? I don't see why'd they bother lying to X1 devs first. People who have the hardware.
It's not a lie if it can happen once in a while but that doesn't mean it is a reliable metric. With no context for the number it seems like a classic PR fact that looks good on a bulleted list but means little for practical purposes. Who knows when those kinds of numbers can actually occur ?
By the way if people are adding up bandwidths can one say that their computer with a gtx 680 now has 260 GB/sec of bandwidth ( 68+192) ? What other kind of bandwidth additions can be used ??