You'd have to look at a spec sheet. But that's what I'm saying, you otherwise wouldn't. However, what you're proposing would pose the same issue as if someone designed an external SSD that could pull from multiple USB 3.0 ports for double the speed; if you plugged both cables into ports that share a controller (and therefor, bandwidth), as is common with most consumer devices, you'd see virtually no benefit. Since individual TB controller cards are rather expensive to the end user, I'm guessing that most peripheral manufacturers are counting on said consumers only having the one included on the motherboard. And, as I've said, if that's the case, then no matter how many ports your device has, you won't see a benefit between using one and any number of more cables