Error while make.

/usr/bin/ld: obj/src/base/sources/GAUtils.o:(.bss+0x0): multiple definition of `GAUtils::sortPopulation'; obj/src/main.o:(.bss+0x0): first defined here
collect2: error: ld returned 1 exit status
make: [Makefile:74: bin/GPX2] Error 1

I have tried multiple ways but still not able to resolve the issue. Any help will be greatly appreciated. 