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When the user is an existing customer starting to use xID at your website, he will have a user account with an associated password. To If you make a connection between the user accounts, to make xID the safer option, please consider removing the existing password connected to the user account. You could instead generate a password that is complicated and unique, which the user never gets to know. This way he is still able to access his account without xID, using functions like "Forgotten password" etc.
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