two different rams

Hi, I currently have the Corsair Vengeance LPX 2x4GB 2400MHz RAM kit in my system. I'm planning on upgrading the capacity so am looking at the Corsair Vengeance RGB Pro 2x8Gb 3200MHz. My motherboard only supports up to 2400MHz but I'm getting a higher clock speed RAM kit as I plan to upgrade...

I've got 2x4GB of DDR3 Kingston Hyperx Genesis ram 1600mhz and I want to upgrade to 16gb. Can I buy another pair of 2x4GB 1600mhz ram although it's not made by kingston? It would suck to buy 2x8gb of ram just to throw the other ones away. There are rams made by Hyperx but I'm not sure if it is...