When using the Wildfly/EAP user management security provider, by both changing a user's password or creating a new user using a non emtpy password, the underlying properties file gets updated with the new hashed password fine but the entry for the user is duplicated.

It does finally works fine as the password is stored on the last entry, so it's being read the last one as well, but anyway the entry should not be duplicated.

Example for users.properties:
---------------------------------------------------------------------
roger=
jack=984ba30e11dda7b9ed86ba7b73d01481
roger=a8c601f01e2d874b0a442c5f9782a7a8
---------------------------------------------------------------------

PS: Affects to current master (7.0-SNAPSHOT) and 6.5.x branches.