EKM strange letters

[Daarom]

The letters are not hammered in but stick out.

[Austrian]

It's from the stamping underlay.
Test stamps were often found on these sheet metal plates.
These pushed through when the tag was stamped.
You will find it on many tags, but usually only rudimentary.

[BlackCat1982]

Yes, no red flag with such markings on the reverse. Nice ekm.