I'm thinking of four actors who survived one episode but were not so lucky in another. The same restrictions as to which episodes, for the same reason: i'm shaky on post-70's Columbo.
Leslie Nielsen died in Identity Crisis but survived Lady in Waiting. James Gregory died in Short Fuse but survived Most Crucial Game. Robert Vaughn died in Last Salute to the Commodore but survived Troubled Waters. Ida Lapino died in Swan Song but survived Short Fuse.
oops I missed Vaughan and Lupino! That means that there are at least 6 correct answers, not 4
I'm coming to it late, but my guesses would be John Dehner, Robert Vaughn, Tim O'Connor and Dean Stockwell. Of course, if you mean that each person got killed in their SECOND episode and survived in their EARLIER one, Dean Stockwell would be wrong.
d'oh! Last Salute is kicking my ass, I need to bite the bullet and watch it already. Dean Stockwell was my second-to-last quiz answer, only one left...
Wilfred Hyde White
The late great Anne Francis!