Welcome.
But to get any significant info, you need to post good pictures.
If it is marked 1918/20 - and not 1920 over 1918- it is just what you say you think it is; they are not rare but uncommon.
Being a mismatch likely puts it into "interesting" shooter status.
Here is a picture of the receiver on my example.
__________________
03man(Don Voigt); Luger student and collector.
Looking for DWM side plate: 69 ; Dreyse 1907 pistol K.S. Gendarmerie
|