That is possible, but not as likely. The 1920 stamp
is found on pistols later than 1920, 1921, etc, but how often is it found on something made in 1927, 1928, and 1929? Jan Still discusses a few much later ones, but they are few and far between.
Until we see pictures of the frame, suffix and if it has a stock lug, then I would think it is an older one, rather than a alphabet luger...
I am not saying it is impossible, but less likely (although you never know

).