I suppose we always have to factor in the possibility that a character may just not know what he's talking about. Some speak very authoritatively, like Stokes, but they're wrong sometimes, too. It's a bit "hypnotizing", hearing a character state something as fact on-camera. It gives the impression that it's the show's position. If this were real life, we wouldn't just trust completely what this or that person says, and maybe that's how we ought to treat all this.
Clark was mostly in the dark about his nature and past, so up through the disappearance, he can get things wrong, even if he sounds sure. Stokes talked about another Jeff Clark, but he guesses his ass off.... Every time anyone refers to "another Jeff Clark", it could mean except in name. It could just be a way to refer to him, since they can't be sure of what his actual name would be.
This is magic, not science-fiction, and while magic should follow some rules, we seldom know what the rules are. It's possible that as Bradford's spirit retreats into the past, Ned's life is no longer suspended, and he reappears wherever he left off when Clark took over.
I'll add that once Bradfordclark disappears, he in fact now has never reached 1968 or 1967 in the first place, since he returns to when he was alive (wasn't he supposed to have gone to the future after death as a spirit?), and then doesn't die the same way. (Let's avoid discussing that altered manner of death.) So Ned's life might not necessarily have any lost time in it while his body was hijacked. Maybe Ned's body renamed "Jeff Clark" never happened anymore.
