Anthony Edwards is going to guest star on ER according to the
TV Guide. So are you asking how will he be able to guest star on the show if his character is dead? No it is not his evil twin brother or his ghost, but instead he will appear in flashbacks to explain why Angela Basset’s character is on the show.
ER is hoping to get more of the stars from the past on the show’s final season like Anthony Edwards and Noah Wyle. Hopefully they will be able to get George Clooney to make a cameo too, they were able to do that once before afterall!