While I have seen a limited number of BCD examples, it is not unusual to see re-numbered parts and odd parts used in their early production. It seems like, in my opinion, they used what they could get to assemble rifles. They seemingly got a lot of help from Walther to get production running, as I have seen several early rifles with Walther/Odd parts on them. It appears that they had to initially rely on others for parts to complete rifles. So, why would they not use parts from other rejected/damaged/sabotaged? rifles to get a good rifle out the door? Also, I suspect the conditions of assembling them were not ideal. Just my opinion here and others may step in with their views.
In this case, who really knows...a rifle that had initial issues and they reused the parts from other on this one...or an armorers repair?