Database error (INSERT INTO `oc_authtoken`) on upgrade from 12.0.0 to 12.0.2

Have an existing 12.0.0 installation.

Saw that 12.0.2 is available so used the online updater. Went through maintenance process with no issue.

Decided to use browser option to update database.

This gave the following text:

Nextcloud
Update to 12.0.2

Doctrine\DBAL\Exception\UniqueConstraintViolationException: An exception occurred while executing ‘INSERT INTO oc_authtoken(uid,login_name,name,token,type,remember,last_activity) VALUES(?,?,?,?,?,?,?)’ with params [“nwj”, “nwj”, “Mozilla/5.0 (Windows NT 10.0; WOW64; rv:55.0) Gecko/20100101 Firefox/55.0”, “7c4821d9befd08675bbc298e545476955b6f18d8e43f348e5deaa1a1e2d304e20af10b73181169cf6c3acd5edbdd98f9d69159e56e09ada3db554f87aceb7ce2”, 0, 0, 1503516295]: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry ‘7c4821d9befd08675bbc298e545476955b6f18d8e43f348e5deaa1a1e2d304e2’ for key 'authtoken_token_index’
Detailed logs
Preparing update
Set log level to debug
Turned on maintenance mode
Updating database schema
Updated database
Doctrine\DBAL\Exception\UniqueConstraintViolationException: An exception occurred while executing ‘INSERT INTO oc_authtoken(uid,login_name,name,token,type,remember,last_activity) VALUES(?,?,?,?,?,?,?)’ with params [“nwj”, “nwj”, “Mozilla/5.0 (Windows NT 10.0; WOW64; rv:55.0) Gecko/20100101 Firefox/55.0”, “7c4821d9befd08675bbc298e545476955b6f18d8e43f348e5deaa1a1e2d304e20af10b73181169cf6c3acd5edbdd98f9d69159e56e09ada3db554f87aceb7ce2”, 0, 0, 1503516295]: SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry ‘7c4821d9befd08675bbc298e545476955b6f18d8e43f348e5deaa1a1e2d304e2’ for key 'authtoken_token_index’
The update was unsuccessful. Please report this issue to the Nextcloud community.

I decided to delete the table contents as its impact seemed to require users to re-log on - and then the upgrade worked without issues.

Though it is unclear what the purpose of the data duplication.