You can distinguish the devices based on the VID/PID combination. This attribute is defined to be a part of the CCyUSBDevice class and can be accessed through an instance of the class.
// Open() automatically calls Close() if necessary
vID = USBDevice->VendorID;
pID = USBDevice->ProductID;
} while ((d < devices ) && (vID != 0x04b4) && (pID != 0x00f1));
In case you have multiple devices with the same VID/PID, distinction can be made possible through the addition of a unique serial number in the device firmware (string descriptors). The serial number can be queried on the host application using the wchar_t CCyUSBDevice::SerialNumber attribute of the CCyUSBDevice class.