For example in TNG "Relics" Scotty rigged the transporter to store his "pattern" and he was this way for DECADES. Wouldn't it be hell if he really was conscious all that time while in that "buffered state"???
But it was an important plot point that Scotty did something truly exceptional there. This is not an example of how the transporter normally works at all.
And again WRT "Second Chances", how exactly can both Rikers be the original consciousness?
Why not? Something like that would be eminently copyable, erasable and whatnot. There'd be no more uniqueness to it than there's to a lump of meat when subjected to the transporter-duplicator.
So one becomes two. What possible reason would there be to claim that both cannot be continuation of the one?