Well, it's often quite difficult to conclude of an individual letter-based symbol on the true manufacturer.
Reino, you're well on the logical path and possibly right; especially a matching WaA-number is a valuable and strong clue.
At this point a look on the product spectrum of these companies might help (or increase the obscureness?):
Hepting & Co. at Stuttgart was, before and after the war, a leather factory, manufacturing belts, suit- & briefcases etc. and very likely during the war military related leather goods.
Herus GmbH at Hanau was very specialized in precious metals (silver, gold, platinum) and made electrical contacts, catalysts and rhodium mirros for Flak-searchlights.
Now I wonder: the belt-boxes were a quite simple tinware in mass production, so why should these two specialists in completely different business areas fabricate such tin boxes? :hmmmm2: