Re-allocate user and group IDs
When this option is set to Yes and you are restoring a server that
does not currently exist on the system, the Unix user and group IDs for the
server administrator and mail/FTP users will be re-allocated to use free
IDs on your system. This is typically what you want as it avoids clashes with
existing IDs on your system.
Selecting No tells Virtualmin to use the IDs that were in use when
the backup was created. This should be used if other files still exist on
the system with the old IDs, and if those IDs have not been allocated to any
other users or groups since the backup was made.