I also have a Luger with a factory over stamped serial number.
We discussed that ;pistol here:
http://forum.lugerforum.com/showthre...ht=overstamped
The trigger plate looks like it may have been factory installed with both sets of digits stamped with the same die font. I've never seen one double stamped like that.
It's very possible that the serialization error was discovered in a final inspection (possibly duplicating another pistol) and sent back for rework to correct the serial and do other work. Unfortunately, there is not likely any documentation of this.
__________________
Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.