Mike,
I must counter the thoughts of my good friends George and drbuster with a much more conservative viewpoint.
There existed a known system to denote weapons whose manufacture was completed in years after their chamber date. There are examples known of Erfurt Lugers following this requirement (
"A Real Two-date Erfurt" (Luger Forum) ; Jan Still, "Imperial Lugers" p.78). One of the known examples has a chamber date 1914/18 (
"1914 Erfurt" (Jan Still's Forum) ).
From a collection standpoint, this 1914 Erfurt will always be questionable due to the lack of a certifiable explanation for its radically out-of-place serial number. While it "could" have come to be by the proffered speculation, this is not enough to warrant its authenticity, or to place a value on it as an original.
Too bad, too, because on the face of it this is a really nice looking Luger.
--Dwight