Qt compiler warning: overriding commands for target / ignoring old commands for target

I got the same error once , maybe source of your problem is different but I will write anyways.
In my *.pro file, it was like :

SOURCES += main.cpp\
    mainwindow.cpp\
    serialHelper.cpp \
serialHelper.cpp

HEADERS  += mainwindow.h\
     += serialHelper.h \
serialHelper.h \
typeDefinitions.h

cpp and header file was repeating itself. I delete the repeating includes and problem solved for me .