How shimmer identifies the same user on different devices ??

[HeenaAgg]

How shimmer identifies the same user on different devices ?? I meant to say if a single user is using Fitbit and Googlefit and then Fitbit will generate the unique id for the user and Googlefit generate another unique id for that user ...when data is collected in shimmer, how do shimmer know that data from Fitbit and Googlefit are from the same user. Is there any way to identify the same user ??

[umarhussain15]

when you authorize the user with shimmer you pass username to the authorize url. So if the username is same in both the Fitbit and GoogleFit, shimmer will store data for both under same username