Board Thread:The Panopticon/@comment-43908-20150311013943/@comment-6032121-20181105215358

Again, Rassilon is a weird, weird case, since depending on who you listen to (Steven Moffat, for example) he may not have ever been dead while he was in the Tomb of Rassilon, meaning there's at least that one precedent of a Time Lord being copied into the Matrix even as their original self is still around.

And I'm unfamiliar with the relevant stories, as you have already surmised, but please enlighten me: is it implied by the Matrix-Trey's appearance that Romana died in that third incarnation? Because if not, then it's another, even firmer example of a version of a Gallifreyan being uploaded into the Matrix even though their original self isn't dead.