There is no such thing as quad channel ram, or triple or double for that matter. Ram is ram and you run it in single, dual,triple mode that is determined by the memory controller and the motherboard architecture. Ram kits are bundled as "dual channel, or "triple channel" meaning that they are ostensibly tested and certified to work together in tandem. usually it means that they were manufactured in the same lot and taken from the line in succession. You can use a portion of a triple channel kit for your dual channel setup, or parts of two dual channel if you like. The only caveat to this is that the 4 GB modules seem to get a little more finicky than do the 2 GB modules. In all likelihood they will work just fine. But you might want to consider shelling out the extra for a certified set.
iPhone X review