Maker marked vs Unmarked badges why?

[steelcase]

I have a small collection, just getting started. Many of the badges are zinc die cast. Why would the same manufacturer produce the same decoration with some badges bearing a maker's mark and some without? Marking the badge would require no extra work or effort once the die was produced. If the mark is on the die it will appear on the badge. I'm just trying to learn. Maybe someone has an explanation for this.

[Christian K]

Different variants. Some makers make a bunch a variants of badges and sometimes they choose wither or not to put a mark. This is just my opinion.