only if you can keep your knowledge intact. It might be harder if you’re on the same timestream just folded back upon itself, in which case each change you made to human history would be instantly known but perhaps the memories of the “you that wanted to go back in time” might be gone.
Depends how Time works. but considering we’re able to hold contradictory ideas in our brain simultaneously, I see no reason that spacetime can’t hold many seemingly contradictory timestreams simultaneously.