As far as I can tell, since I too wanted this information, Apple Configurator is not storing it. All of the Apple Configurator state (for users, apps, and in this particular case of interest, devices) are stored in two SQLIte databases. As the currently running user of Apple Configurator (it depends how you use it), they are in:
~/Library/Application Support/com.apple.configurator/AppleConfigurator.storedata
~/Library/Application Support/com.apple.configurator/Users.storedata
The names should be self-explanatory, but more or less the latter is blank for me, probably because I do not set users for the iPads we loan out in our organization and deployment model, so there is nothing to correlate to my empty user list. However, if you look in AppleConfigurator.storedata, you will find a table called ZDEVICERECORD with the following columns:
Z_PK
Z_ENT
Z_OPT
ZNAME
ZSERIALNUMBER
ZUDID
As you can tell, the only two columns of value to us Administrators are something we could already determine without look at the internals: the device's serial number and the Unique Device ID which is tied to a specific installation of iOS on an iPad or iPhone. I have seen mention that turning iTunes into Activation Only mode will help, but I call shennanigans. But when I have some iPads back I will try this and see if that data is stored. I am skeptical.