Fixed a bug where the fluxes were added twice accross processes when using MultiFrameInstrument
Fixed a bug where the fluxes were added twice accross processes when using MultiFrameInstrument


Former-commit-id: 5aa2f9d74dba063a970e684b8b574240182bdf24
SKIRT/SKIRT,raesjo/SKIRT,SKIRT/SKIRT,raesjo/SKIRTcorona,SKIRT/SKIRT,raesjo/SKIRTcorona,raesjo/SKIRTcorona,raesjo/SKIRT,raesjo/SKIRT