Dear Obetz,
The two devices are the BDM proper and a CDC serial interface. The documentation for the latter is incomplete. - Sorry!
The two devices in the composite device support the usual BDM interface as well as a serial over USB interface. They are pretty much independent so you do not need to install two drivers unless you want the functionality of both.
Install the libusbV1 driver for
VID_16D0&PID_0567&MI_00 USBDM BDM interface
as described in the documentation (with some changes to names!) here:
http://usbdm.sourceforge.net/USBDM_V4.3/USBDM_JS16/html/index.html
The other device is a CDC serial driver. The required inf file is in the driver directory however I'm unsure if the hardware you are using supports the serial interface. If not, there is no need to install the second driver.
The JMxx firmware build in V4.3 accidently included the CDC feature - It should have been disabled for this hardware version. This is probably why it appears in the hardware you are using.
bye