For most of what I write, the person needs to be nearby, I will store the key, the realname and the display name.
I will use display name for hovertext and dialog, but for comparisions it will be the key, and in the event of dispute i will produce the reall name.
eg; they select Julie from the dialog, my key doesnt match the Julie that is nearby, so iI can then pop up a message saying i mean this Julie and give the reall name.