They're sadly uninformative, both in store and on the website.
To provide any decent security they should be different not just to other makes but between packs too - so buying a new set shouldn't even be a way to get a replacement key. However they may be less secure than that, with all sets being the same.
My Pinhead security skewers (I don't know why they call them "clamps" - they're not clamps) and other fittings have many variations for the same model. Replacement keys are available with the number printed on the key or a card you get with the set. That's normal for locks and keys.
They may be someone else's low-security product rebranded, in which case a replacement toolb(it's not much of a key if they're all the same) might be available.
If they're worth having in the first place, you're in the normal position of someone who's lost their keys, which is usually an expensive and destructive error.
On the whole, if you can just buy a replacement set and get away with it, I'd say you've got off pretty lightly. You should inspect the ones in the shop to make sure they're the same as each other, seek assurances from staff that the tool from another pack will work, and ideally try it out there and then at the shop.