In a dramatic moment, Rob reveals to have been Bob all the time; he was just pulling an act to fool his enemies into making them think he was dead.
Alternatively, Rob seems to be similar to Bob in many ways, but Character Development goes quickly enough to make Rob less like Bob.
Double Subverted: ...However, Rob doesn't know that that claim is only partially true, because he's a clone with the memories and personality of the late Bob, which means the original was Killed Off for Real.
Averted: While Rob now covers Bob's role, he's different enough that no one can establish a true parallel between the two of them.
"After Bob's death, we received a great amount of input from fans who wanted him back. However, that would have been impossible without altering the in-story rules and emotional tone. To compensate for that, we gave Rob a lot of Bob's most popular characteristics, but the fans haven't received him too well."
The actor who portrayed Bob had to leave for personal reasons, but his character is still important to the plans the creators had for the plot, so they bring in a new actor and give him a very similar characterization to fill the role in later plot-related events.
"Hey guys: 'I Can't Believe It's Not Bob!' We guarantee your total satisfaction, or we'll refund your money!"
"Rob, such a plucky, strong guy. Reminds me of someone dear to me."
Invoked: Rob turns be an infiltrated agent that studied and mimicked Bob's personality to gain the group's trust faster.
Exploited: Bob's survivors physically and psychologically heal more quickly thanks to Rob's presence.
Defied: The group actively discourage Rob from any conduct remotely similar to Bob's; they feel extremely uncomfortable about it.
Discussed: "You know, all things considered I think we'll just call you Bob II from now on." "Inconceivable! I'm nothing like him." "See?! You keep using that word! 'Inconceivable' used to be his catchphrase."
Conversed: "I understand that Bob's actor had to leave the show due to health problems, but this replacement gimmick was so lazy that I could bet they just erased part of the first 'B' every time the name 'Bob' appeared in the script and called it a day!"
The psychological impact of Bob's death is so deep, that the group forces Rob to emulate his personality, skills and even appearance. The stress of having to live up to his predecessor's name also leaves a great mark on Rob, which eventually causes him to lose his own personality as he transforms into a hollow shell that looks and acts like an imperfect Bob copy.
The group keeps discussing the superiority of Bob vis-à-vis Rob. Rob does his best, but can't fill the shoes of his predecessor. Eventually the stress of trying to be someone he's not drives him to suicide.