Let’s start with some basics which are more or less known. Each infantry replacement battalion under original German replacement system (timeframe 1939 – Autumn 1942) was composed normally of reception company, four training companies and one or more convalescent and transfer companies. The primary purpose of this battalion was to receive recruits, train them, and dispatch them as replacements to the field regiments.
In October 1942 very signifant change to German replacement system had occured. All basic replacement training units were divided in two parts – one to handle induction and replacement and the second one to deal with the training.
The induction and replacement responsibilities were retained in replacement battalions, but since this moment it was concerned only with:
receipt of recruits from the conscription offices;
issue of their personal equipment and their paybooks;
short military indoctrination of recruits;
forwarding of recruits as fast as possible to its sister training unit;
receipt of convalescents and sending them back to a field unit.
The newly created training unit bore the same number as the replacement unit and was to receive the men from the replacement unit, give them the training and then dispatch them to an affiliated field unit.
Now, we can jump into Stamm-Kompanie. This coy was consisting of new recruits and cadre personnel and its main task was exactly reception of recruits, induction procedures and forwarding them to the training unit. It means this coy was designated mainly for administrative purposes and didn't provide training at all. I think that's the reason why so many recruits went through it and why plenty of ID tags with reception coy’ stampings are being found.