Looking over your photo, the side plate 2 digit number compared to the left side 4 digit s/n, the side plates number is defiantly larger, easy to spot. The Luger on GB I'm looking at, there seems to be little different size between the side plate number, and the 4 digit s/n. If you look at the close up photo of both sets near side by side, for what I measure from the photo, IMHO, they are of the same size. More so when you enlarge the photo.
Then again my eyes might need to be recalibrated !!