Hi Austin, That is a very good question. Unfortunately not. You either choose a DisplayPort or HDMI to output to 4K. The second port will give you a max of 2048×1152. Find out more about USB Graphic here
You want to connect 2 x CSV-3103D to 2 different USB3.0 port on you PC and connect a 2560x1080p screen ot each of the Docking Stations ? Yes that is possible. And i don’t see why connecting an other screen to the HDMI Ouput of the Grpahics Cards would be an issue either. That should work.