Issue

Duplicate records are registered to mgmt-groups.properties or application-roles.properties when adding an user with an empty group name as follows.

Use -g option with an empty string when adding an user by add-user.sh.

$JBOSS_HOME/bin/add-user.sh -sc ./standalone/configuration/ -u testuser2 -p password -g ""

Or in the interactive-mode, set to blank for the group name answer.

$JBOSS_HOME/bin/add-user.sh -sc ./standalone/configuration

What type of user do you wish to add?
 a) Management User (mgmt-users.properties)
 b) Application User (application-users.properties)
(a): a or b
...

What groups do you want this user to belong to? (Please enter a comma separated list, or leave blank for none)[  ]:
// set BLANK

After that, mgmt-groups.properties / application-roles.properties will have the duplicate records as follows.

testuser1=
testuser2=
testuser1=