Hi John,
I do not think anyone implied that the "10000" was monkeyed around with. Rather, the speculation was that a "GL" might have been added at some point in time.
The "GL" could be added with a custom-made stamp, or maybe a very old rear link from a worn-out GL luger was just transferred to this gun. Taking a commercial 10000 numbered gun into the high dollar world of a "GL" made gun...
But I, vote, that this gun was certainly refinished...from the photos provided...
Regards,
Pete...