Getting an error while creating multiple users using the webservice 'Create User'

We are getting an error while creating multiple users using the webservice 'Create User' when any of the users already exists in Unifier. We can create multiple users only when none of them exist in unifier.

Ideally, it should create users which are not there in unifier and just ignore the existing users. Basically, the API is working as all or none case.

In the below case, if users a2 and a3 do not exist in Unifier, then the webservice will create both the users in Unifier successfully.

But, if any user (let say a3) already exists in Unifier, then the webservice will not create a2 as well.