问题
I know that you can pass two provider tokens to merge them to use the same identity, but what if the user logs in through facebook on their ipad and then google on their phone? How do these get merged by aws federated identities? Is the user going to end up with 2 separate accounts?
回答1:
To merge accounts as you described, the user has to pass both login tokens at some point, just once. Once it has been done, they only have to pass a single token on any future login and they will get the same identity.
So, in the situation you described, if both tokens had been passed already, they would get the same identity. If they hadn't been passed together, there would be two.
来源：https://stackoverflow.com/questions/45022118/how-does-aws-cognito-merge-identities