Sorry, I must be confused.. You can't use 2 clients (using the same LFS licence) to find yourself online, the master shouldn't let you do that as it would constitute using the same licence twice, online. You also can't use "find a user online" for local games that don't use the master.
Locally also unbanning yourself shouldn't make a blind bit of difference (unless there's an interesting tie-in [read: bug] with the ban list on a client affecting a username lookup).
/unban USER wouldn't unban a master server ban, only a local one.
Or were you actually trying to do something else?