... Well, not really the same, technically Susan "died" the moment she turned into a full Red Court Vampire, that's when Harry cut her throat with a knife. In that moment she was no longer Susan, but the youngest Red Court Vamp...
No, there was a moment there where
both were alive. Susan was
dying (it was inevitable) but not yet
dead, the Rampire had been born but not taken full control. They both existed within Susan's body at one time.
Susan
helped Harry in that moment; fought against the Ramp, kept it from fighting back effectively.
Harry killed the Rampire... but also Susan (albeit he only took a few moments of her life, which she gave willingly).
... However except for the part of the anatomy affected the two deaths were nothing alike ...
Enough alike (bleeding-out in Harry's arms, from a neck-wound) to traumatize / re-traumatize Harry, for sure!
... Why do I get the feeling that Murphy isn't going to be the Murphy that her fans love in Mirror Mirror? Remember in the original Trek episode that Jim is sort of modeling this after, alternate Kirk was a no good villain in the alternate universe, in fact Kirk tells the alternate universe Spock to kill him and become captain.. Now Murphy could be basically the same in both worlds as Spock was, but that seems too easy.. Either way it is going to mean for pain for Harry.. Murphy evil and Harry maybe even having to kill her himself.. Pain.. Her being the same Murphy in both worlds and Harry having to leave her behind... More pain.
Hurting Harry any way it goes down -- yah, that's a given.
My own feeling is that Murphy is still going to be one of the "Good Guys." She'll be fighting the Good Fight, fighting against the Dark... including Harry. Harry's Choice comes "near the end" of Grave Peril (per WoJ). The fandom is split on where exactly that choice occurs, but remember: Harry's "alliance" with Murphy isn't really solid, yet.
She will have zero trust for Harry Dresden, because everything she knows of him will have told her he's one of the Bad Guys. WoJ says mirror!Harry is tight allies with freaking
Mavra! Murphy having
zero willingness to trust him will be another quantum level of pain for Harry (if there's really an eyepatch!Murphy, I bet it was mirror!Harry who cost her the eye, so more guilt (
stupid guilt, but guilt (Harry buys his guilt wholesale, in bulk loads, and often gets shoddy stuff))).
In addition to the ST:TOS episode, I think there's WoJ that Harry will be seeing some Jimmy Stewart /
It's A Wonderful Life sorts of action in his Mirrorverse. Dunno if that means Uriel will be showing up?
But Mirror!Karrin will be a darker, more cynical character. She'll have seen loads of ugly shit go down, and
not seen Prime!Harry standing up to it, and winning. Mirror!Chicago will be a darker & less-safe place to be, including for the cops of SI (Rudy, inevitably, will be in charge there).