[MFC]

This is one explanation that I saw on the forum:
Commercial Lugers exported to the US, had GERMANY stamped on them. This is in accordance with US law, that all items imported must have the country of origin on it. Since the Luger was already stamped, the mag that was in it didn't need the stamp. Replacement or second mags had to have the stamp.

I beleive the only commercial Lugers that were sold with extra mags as a packaged deal, were the cased sets. Any other combination of a Luger and accessories were purchased seperately.
GERMANY or MADE IN GERMANY stamps can be found on many different places on Alphabet commercials. Some are even stamped upside down. These are all export stamps. Import stamps are usually the name or logo of the importer.