One option is that the last number could be some kind of production number, refering not to the leather dye lot, which is on the silver tag, but to the entire group of bags that's produced at one time.
Bal probably makes 1,000 Anthracite Cities at one time, then 1,000 Black Firsts, etc (or whatever the production number is) so that all the sewers are matching the same color leather at once.
But at some point later, Bal produces another whole batch, which gets a second number, sometimes similar, sometimes not. And then maybe a third or fourth batch, depending on the number of orders from the stores.
So, for example, there would be many batches of Ink Cities produced if they kept those batches smaller because they weren't sure the color would sell, but then kept producing more small batches as the orders came in.
Just a thought.
Bal probably makes 1,000 Anthracite Cities at one time, then 1,000 Black Firsts, etc (or whatever the production number is) so that all the sewers are matching the same color leather at once.
But at some point later, Bal produces another whole batch, which gets a second number, sometimes similar, sometimes not. And then maybe a third or fourth batch, depending on the number of orders from the stores.
So, for example, there would be many batches of Ink Cities produced if they kept those batches smaller because they weren't sure the color would sell, but then kept producing more small batches as the orders came in.
Just a thought.