Woo-hoo! FINALLY...I got both Kinect 2 sensors running on the desktop workstation.

As shown above test, both sensors are maintaining the max 30fps on a single computer. One Kinect 2 sensor is plugged into a USB 3 port on the motherboard and a second one is connected to a USB 3 port into a PCIe controller on the same computer. This PCIe card is my old USB 3 controller card with the NEC Renesas chipset. The onboard USB 3 controller has the Intel chipset.
Note: The Intel and NEC Renesas USB 3 chipsets are recommended for Kinect 2.
Be aware that that newer USB 3.1 controllers tend to have the ASMedia chipset which is NOT compatible with Kinect 2, so be sure to check the specs online before buying. If you shop carefully, there are some USB 3.1 cards with NEC Renesas. (Even though I don't need a 3.1 card for this purpose, it is a much faster card.)
So, in
theory, it appears I may soon have a total of 4 Kinect 2 sensors up and running since I can additionally run 1 sensor on the new laptop and 1 sensor on my old tablet computer. (Maybe...I'm not sure the tablet was able to maintain 30fps with the RGB video stream required for Maglite calibration.) I'll post more info when I find time to perform a complete capture test.
User Tips:
Attach the sensors one at a time
after you launch Recorder 4. If you attach them both before launching Recorder, it might not pick up the second sensor.
As mentioned in the docs, you'll want to disable Autoplay. At first, I thought I could set each sensor to 'Take no action', but Windows still kept re-scanning for them for some reason. Finally, I just disabled Autoplay completely, which is probably okay since I always found this feature pretty annoying.

Question: I noticed that in the Recorder 4 Home screen, the 'progress' icon keeps spinning and stopping repeatedly for some reason. Is it supposed to do that? It probably doesn't matter since the two sensors are obviously working. Thanks in advance for any info.