When the tool runs, the IUSR_METRO is deleted on all the currently configured PC Server and Hosts and the new PC User account is created, as expected.
The problem is the Delete Old User setting is not used when another new PC Server or Host is installed and Add Host performed in PC Lab Management. Consequently the new PC Server or Host will have two PC users in the machine's Administrator group: the default IUSR_METRO and the new PC System user. This unexpected behaviour may only be noticed when the Windows Users and Groups configuration is checked on the new PC Server or Host.
The changed PC system user entered in the System Change Identity tool is stored in the ALM-PC LAB_PROJECT database and passed to the new PC Server or Host when these are added through Lab Management > Add Server or Add Host. However, the status of the Delete Old User flag is not stored in LAB_PROJECT and therefore this action does not occur with PC Servers or Hosts added from Lab Management. Consequently the IUSR_METRO user must be manually removed from the PC Host or PC Server that is added from Lab Management after the System Change Identity tool has run.