The cross top left is definitely a 1914 EK I; the one worn in the center is most likely the
Militär-Verdienstkreuz 1. Klasse [Military Merit Cross 1st Class] of the Grand Duchy of Mecklenburg-Schwerin, which was of somewhat similiar design:
https://www.ehrenzeichen-orden.de/deuts ... -1351.html
(Although I don't have a list of Hamann's decoration, this one is certainly plausible, too, as Hamann was from Mecklenburg-Schwerin.)