How AE Tells the Difference Between Signups and Logins
Let's say that a member has already signed up to your website using one of their social media accounts and they have forgotten. If they try to register with that same account again, they are signed into their existing account instead.
If a member already has an account, then registers using a separate social media profile, AE will attempt to identify and merge the two accounts. For more information see our article about matching and merging accounts.