I believe that Hcigar serials are unique. I have 3 of their Hammers. The first two came from the same vendor, only a few weeks apart. I got #009 and #064. I bought the third one from somewhere else a lot later on, and got #3868. The switch had also been redesigned- on my first two, the switch was very short-throw and used the wimpiest spring that I've ever seen. There was an incident where I set one down in such a way that the button was just barely touching a camera, and the spring was so weak that it happily cooked off a quarter tank of juice before I noticed the smell of charring wick.. Then they got converted to magnets, and are much better for it. The third came with a slightly longer switch throw and a greatly improved spring. It also ended up getting magnets, although it didn't really need them.
These markings are all cut by a laser that's under computer control, so it's not like a human needs to mess with dies or anything in order to create unique serial numbers. They just have to program the computer to increment the number on each pass of the laser.
