Yes no relation with the fight of JR 117 in 1914. In the case of a wounded soldier sent in a Feldlazarett, there is no reason to see such a writing, as the soldier here didn't become prisonner after.
A exceptionnal set pickelhaube/Uberzug ! As OJR 91 raised I/RJR 74, there is a logical connection between the two units. I would say a lack of plates which needs to take what was avalaible. The stores asked help and received what was available.