Electrode/Filler Wire Selection for P-45 (Duplex)

in WPS prepared and approved in my last project in SAUDI Jubail for Duplex :ASTM B366(UNS NO:N08825)42Ni-21.5Cr-3Mo-2.3Cu, it is found that the chemical composition analysis for the filler wire(AWS 5.14 ER NiCrMo-3)/electrode(AWS 5.11:ENiCrMo-3)/ is as such: nickle 64.4 chromium:22.27 molybdenum:8.72 copper:0.01 for AWS A5.14 ,and it is the same case as for filler wire here is my question why the electrode/filler wire nickle composition is way too higher than that in basemetal nearly by 30%.

if it is a method to guarantee enough nickle especially in welds , is it wastefully unneccessary ,and in this case can we replace this electrode/filler wire with one of equal nickle value, and in similar case what determines the electrode/filler wire selection