How to get a unique device nummer

[funhall]

I like to know how I can prevent the same person to log in to my app with 2 different emails. So can I get a unique device number to tell me that there have been logget in from this phone before?
Can I set a stored variable that dont delete if I delete the app and install it again???

[jared]

I would use the push notification component to get a user id. i think this is device specific.