First, thanks to all for all your warm welcome!

I have checked the dial from different angles and with different light, but I can not see any overprinting.
I think, that should be quite right, because there are different dials out there.
First, there were the overprinted dials with rectangular lume (as other carreras).
But there are other (later??) dials with no overprinted logo and lume points (as mine).
We have had some discussions in german uhrforum: https://uhrforum.de/dugena-poor-mans-carrera-frage-zur-leuchtmasse-t286279
I think, the first dials are overprinted Heuer dials and the later ones were produced only for Dugena (and with lume points).
But I cannot verify it with advertising pictures.

The serial number is in the 156xxx and the ref. number is visible:

Nevertheless, imho it is one of the nicest possibilities to wear a tricompax chronograph from the 70s.

Have a nice day and a good start in the weekend,
Peter