Interesting item. This actually answers a question I have had for some years to do with an M.1915 Shako plate (grey metal steel) on a mint example shako, that judging by it's mint condition it must have been a Liberty War Bond prize.
My example has a one-piece struck plate. But the wording "1860 Land" is at 9 o'clock and not 6 o'clock at the base of the plate. It appears that the striking die may have been two-piece, but for some reason was assembled out of (the correct) alignment. I have never seen another version like this before. I posted an article in the UK "Armourer magazine" some years ago but never had any feed-back.
All I can assume (in my hypothisis) is that the quality control and issue through the BA of M.1915 models was not as stringent as pre-August 1914. Maybe this slipped the eye of the inspector, but I note that my shako has only the manufacturer's ink stamp and not the BA depot stamp evident. Didn't get issued officially to one of the two regiments (Royal Prussian Guard Btn, or RoyalPrussian Schutzen Btn).
Refs: "Jager & Schutzen - Dress and Distinctions 1910 - 1914" by Kinna & Moss (1977) - an excellent reference source.
Hope this is of interest.
Regards,
Mart Vear.