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Judging from the image you posted, seems they follow the convention of the majority of motherboards (slots spaced apart are different channels, and the same colour is used for slots that should be populated at the same time), but they just coloured the retention brackets instead of the whole slot.
You should populate white slots first (DIMM 1 and 2, weird numbering), then you will have dual channel. It is good to check with CPU-Z to make sure it is working as we expected. There is no downside or risk of trying a combination.