I\'m developing an app for my company and we\'re going through the process of slowly letting people into the \"beta\" by adding their iPads to the company\'s iOS Dev Center
Found a nice way to handle it:
Add the app to testFlight.com and give the link to the user you want his UDID.
He will see an error message saying "your device UDID: xxxxxx is not registered" and the UDID will be the correct one.