According to that log, there is only one drive being detected for the Irex (Drive H

and Calibre thinks it is is the main memory from the USB id information.
Note: It is possible to disable the auto-detection of device by disabling the iRex plugin under Preferences->Plugins->Device Interface plugins and then use the "Connect to Folder" feature within Calibre to get a folder treated as a pseudo-device. Which way you go is up to you.