pics then it is just an assumption on your part that the modules are all the same
But please share the photos if you have them and then we can compare and see if any changes were made.
I suspect ALL perpetual calendar modules are relatively similar BUT if a single minor change is made, then DD can claim that it is exclusive to MB. They can rightly also claim that it is a custom module for MB. Whether we, as consumers, are willing to accept this as fact (or "marketing gimmick" for some) is completely up to us.
I've shown you in the post that I made, that TickToc referred to, of what a previous DD perpetual calendar module looks like on an ETA base from a watch I personally owned and had serviced. It is obviously different that the one found on the current MB Heritage PC. Which one is better, which one is more serviceable? Any watchmaker will give you their differing opinions on this.
I'm sorry to be so blunt but your assertion "The list of brands which used this combo (with ETA 2892) in the past is huge, like Bucherer, Movado, Kelek, Nivrel, Frederique Constant" is not correct and quite honestly misleading to describe the MB Heritage PC.
If you don't like it...that's OK. If you don't think it is anything special...that's fine too. But if you want to make assertions and comparisons please provide some proof.
Warmest, Mike