The scenarios below may help shed a little light on the question ...
I purchased a Banana Bone EO 25 a year or so back when they were gettin' scarce. Seller advertised it as Unserialized. When I got it, it was marked with serial #01. Don't recall if it has a COA or not - I think not because I am pretty sure the tube markings didn't show it as having a serial number. I'll have to check. Now I've heard rumor that GEC keeps the #01's for the factory display or for Bill or Ken's (at the time), discretion. This is pretty much "I heard" type of info, so not putting a lot of stock in it until I get it from a more reliable source.
I was also fortunate enough to snag a '1 of 1' from GEC (saddle brown White Owl), and while the tube says "1 of 1", the knife is marked with serial #02 … sooo, do they make a serial #01 knife with each serialized run, or don't they … ?
If anyone can elaborate on any of this, I'd be interested to hear …
~ Edge