I don't believe that is correct Pawel. My US 1968 280sl vin 2074 has 3 keys. They are original and stamped with the numbers that match the data card.
Lori, thank you, you are correct that I may not be correct...
I took it (probably too quickly) for ignition key change. I checked the door and trunk.
Ignition - key change at 043 002980, I guess together with steering column, key is called Master as well, which is probably wrong. This is the only change to switch, lock and key the system mentions.
Doors: master key appears at 044 010356.
Trunk: master key appears at 044 010356.
Fuel cap: no info.
Glove compartment: no info. Just info it is same as trunk.
So my vote would be for change at 044 010356.