So checking the Marvel Wiki, I was intrigued by how several characters are listed as still being dead, and have been replaced by clones or copies. Notable among them being Loki, Black Widow, and Doctor Octopus.
>https://marvel.fandom.com/wiki/Loki_Laufeyson_(Ikol)_(Earth-616)
>https://marvel.fandom.com/wiki/Natalia_Romanova_(Red_Room_Clone)_(Earth-616)
>https://marvel.fandom.com/wiki/Otto_Octavius_(Duplicate)_(Earth-616)

Curiously, Iron Man isn't listed as dead with a clone replacement even though the comics have explicitly stated that it's the case. None of the mutants brought back by the Five either.
Seems a bit arbitrary is all I'm saying.