Wouldn't cutting duplicates to the existing key be better for locks and keys that have worn together over the years? I would imaging that a new cut-to-original-code key wouldn't work smoothly in an old lock. I had that issue with trying to get a duplicate ignition key for my bike. The new key worked about 1 out of 10 tries.
I have read that before, but after cutting Goldwing keys by code for 3 and a half years now, the most common comments are "Works perfectly" and "Works better than the key I had." Based on that, I'm not sure I believe you 'need' a worn key to operate a worn lock. But there may be exceptions.
Any copy of a key will be slightly off from the one it's cut from. A copy of a copy will be even further off from the original. I think of it like a xerox copy of a xerox copy is just not as sharp as the original document.
Plus in the case of the early Goldwing keys I cut, there are 4 different key blanks and over 1000 total key codes. Without cutting by code, I'd have to have a lot of money tied up in a lot of keys to make duplicates from. I have cut over 500 keys so far, and that's not 500 different codes so the majority of the codes I have never cut, and may not need to, ever.
I am still thinking on the Hudson (and other single sided) keys. Those blanks (Y11) are as common as dirt and you should be able to find someone locally to cut them for cheaper than I can, once postage and fees are added in. The y11 blanks are MUCH cheaper than the D8777 so I am initially anticipating that I could cut and mail a pair of them for $5.00. But there are soooooo many code series and codes, I don't know if it's feasible to pursue. Without code books and a method to cut them by code, the only way would be for you to send me your key and I send it and your copies back. Not an optimum solution.