Duplicate entry 'entry' for IDENTIFIER

I removed the user with identifier XYZ.
When I tried to add new user with that identifier I get error:

Duplicate entry 'XYZ' for key 'uniqueid' - SQLIntegrityConstraintViolationException (... < QueryBuilder:469 < DatabaseStorage:95 < BaseObjectResource:73 < ... < OverrideFilter:50 < ...)

How to override this?

Did i do something wrong?

Why dont you look in the database. Any ai can explain you how to check those things.

When I deleted the user, why the database entry is not deleted? Is it normal behavior to manualy delete this stuff?

I removed the DEVICE not USER, my mistake.

Yeah, you could see in traccar itself that the User still exists. And also that the device was removed. And if you think that is not true you can check the database.

If you remove a device with a lot of data, it is possible that the operation timed out and didn't actually succeed.