Hey @sanchit 

Is your implementation set up correctly to assign a new user id based on the new registration event?

In the 2nd case it seems like the user id for Person 2 is the same as Person 1 i.e 1234.

Here’s an article which explains the concept of Multiple user IDs on the same device really well.

Hope this helps.

HI @sanchit ,

Thanks for writing into the Amplitude community!

I agree with @Saish Redkar ! The implementation sounds like new users are being assigned the same user ID which would merge them to that user. If the new user registers, I would assign them a completely different User ID to avoid them being merged into user with the ID of 1234. The article Saish mentions is a good resource to go through this and see. 

I hope that helps! Let us know if you need any more help!

The problem is new user is assigned user ID when the user complete the registration process, 
I will give you the example

There are 3 screen process for registration

Screen 1 - Name

Screen 2 - Address

Screen 3 - Phone number

Person #1 complete the registration process and his details are as follows

Name = N1

Address = A1

Phone number = P1

User ID = U1

now he logout of the device and again this 3 step registration process starts

Person #2

Screen 1 - Name = N2

Screen 2 - Address = A2

so if the process is completed till here, amplitude update the User ID = U1 with

Name = N2

Address = A2

as new user ID is only created when the person completes the full registration process. Now we have wrong data of Person P1 in U1.

HI @sanchit ,

My understanding of this is that the user is being set a User ID U1 which already exists, and therefore Amplitude will assume it is the same user and merge it. Is there a reason you are assigning the same User ID to a new user? You would need to implement it so that a new User ID is given for the new users. I would look at your implementation and instead of assigning a new user with the same User ID of U1, I would wait til after the full registration and then assign a new user ID that does not exist in the system. 

Does that make sense? Is there a reason you are assigning a user ID of U1 for every user who comes to register? Or is it only if they drop off at screen 2? In this case, you would need to examine your implementation and ensure that setting a user ID only occurs after the registration.
@Saish Redkar , thoughts?

Agree with Denis here.

It would be ideal that the user be anonymous till screen #3 and then once the registration event is completed, then only assign the user ID. You may have to test out this scenario and see which one plays out better in your use case.