The FIDO U2F standard does not state an official opinion on multiple keys per account, however it should be trivial to add. I am surprised that engineering would only allow 1 considering how common it is to carry a backup. But you know Twitter engineering 
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Well, 1 is one of the 3 interesting numbers in computer science, so I *get* why they designed to support only 1.
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Shouldn’t campaigns be encouraged to use TweetDeck teams to avoid sharing full account credentials and have selective revocability?
Thanks. Twitter will use this to make your timeline better. UndoUndo
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