Can I travel to Canada by taking my old and new passports together?
You have to carry both the passports on your travel. Old passport, as it bears the visiting country's visa and fresh passport as it is the current and valid one. As a matter of anecdote, you might have read recently in the newspapers, as one of the IAS officers on entourage with the state chief minister, caused delay of Air India flight as he forgot to bring old passport bearing US visa to Mumbai airport and was carrying only new passport.