I made a huge mistake during my recent trip. I got the 3 souvenir stamps on my canceled passport and then realized that I might still need my old passport for future travel. I still have valid long-term US/Canada and UK visas in that passport.
How likely will it impact my future travels to these countries? I am aware that unauthorized stamps could be considered tampering. Is there any way to fix this issue or should I already apply for the new visas?