Lets say, just to add a bit of a story to the question...
you were walking along the road and came acorss say a genie and instead of granting you three wishes he tells your future and shows you what life is going to be like in 50 years.
Regardless of whether your foretold future was good or bad. The fact that you now know your own future will probably mean you behaviour or a few things in ur life will change, ven just small things that wouldnt have altered if you didnt know your future. So would knowing your own future and therefore leading to a slight change in behaviour render this future invalid or would the foretold future include the change in behaviour u experience due to knowing this future.
Some people (forget which belief system now) believe that time flows in a circle so that everything that happens has already happened and will happen again, and again and again. So you could have met that Genie a few times