Disallow duplicate device usernames

What is disallow duplicate device username functionality?

If disallow duplicate device username functionality is enabled - it does not allow users to create duplicate usernames.

Duplicate device usernames can lead to confusion when reviewing and gathering statistics.

How to allow/disallow the creation of duplicate device usernames?

To disallow users to create devices with duplicate usernames tick a check box in Setup -> Settings -> Various menu:

Other notes

It is recommended to enable this setting and disallow the creation of duplicate device usernames.