Excellent questions! It could be a paradox, like Anna suggested, or an unpredictable outcome. Either way there's a lot of food for thought here.

I love time travel! It can become so convuluted but simultaneously be fun laugh

Granny Weatherwax: 'You've got to think headology, see? Not muck about with all this beauty and wealth business. That's not important.'

Wyrd Sisters, Terry Pratchett