We may have some cases where the same user can be synced from different AD domains, or we are transferring our domain to a new one, and some users already synced from the old and the new one as well.
For such cases, Device2 supports the login, but we need to be sure that the username must be in different styles where it is synced from different domains.
For example if the username style under
Tools -> Settings -> Active Directory Settings
has been chosen like this for more than one domain
the user will not be able to login.
The adjust these cases, we need to use Domain\username or username@domain styles
and to not use any "default" domain at the bottom of these settings
If the users already synced by the old naming style, we need to delete and resync them once again, as changing the naming style will not affect the existing users.